How Much Force A Bullet Exerts Against The Rifling

[vzerone]

More correctly how much force a bullet exerts against the sides (or walls) of the lands. I have a formula for that, but their are a lot of variables. One is the number of rifling grooves. Another is where you calculate for the pressure meaning this formula is for peak pressure (or when the bullet is moving at it's highest velocity in the barrel). The example in the formula is a .25 caliber bullet with a velocity of 2500 fps fired in a 1 and 12 rifling with 6 grooves. The answer is 4900 pounds. We know that a faster twist would raise that number. Now do those of you still feel that the torque applied to a cast bullet is enough that it is indeed the faster rifling twists that is damaging the bullet in some manner that it becomes inaccurate? Here's the formula:

157154

[DougGuy]

No one that I know can read that 29kb file and if you blow it up to a readable size you still can't read it. I don't agree at all with your math. If a rifle had that much torque applied against the rifling, NO HUMAN could hold on to it and fire it.

[geargnasher]

Didn't I mention that to you in email like a year ago? Right there under our noses in TBF all this time. I did calcs when I found that for M1A 11-twist and bearing surface of engraved (but not bumped-up) 30 sil. bullet, came up with around 10K psi on sides of lands at 2200 fps, way under 50/50 alloy strength. Pretty much settled what we and DrB were talking about way back....bullet ain't gonna strip unless it's made from linotype or similar that will literally abrade away at hv. Gotta have the right alloy for pressure/velocity which means not hard/bittle/flaky and not too much tin....like SOMEONE has been telling us for years.

Gear

[vzerone]

No one that I know can read that 29kb file and if you blow it up to a readable size you still can't read it. I don't agree at all with your math. If a rifle had that much torque applied against the rifling, NO HUMAN could hold on to it and fire it.

Well that is your opinion, but I don't agree with it. The formula is correct. Take for example if the peak pressure pushing the bullet is 52,000 PSI what would you assume the force of the bullet against the rifling to be, some very low number? BTW the the physicist that figured these formulas up also were questioned as to what was the force in pounds that the bullet torques or twist the rifle in your hands and it's very very low. An example figure like .031.

I'll try to enlarge and repost that image.

[geargnasher]

No one that I know can read that 29kb file and if you blow it up to a readable size you still can't read it. I don't agree at all with your math. If a rifle had that much torque applied against the rifling, NO HUMAN could hold on to it and fire it.

If a rifle put nearly 3,000 lb/ft of energy into a bullet it would knock you over backwards 20 feet if you fired it......Except they DO and IT DOESN'T. I think you're not understanding about the A in F=MA, DougGuy, or the scale on which these forces are applied. You can actually feel the torque of a .308 rifle or even a handgun in your hand if you pay attention to it.

Download The bullet's Flight by F.W. Mann from Castpics and read the whole section that page is from, it gives a full explanation of how the formulas was derived with consideration to certain parts of the equation which make it not precisely accurate but so nearly so as to be inconsequential for our purposes.

Gear

[vzerone]

Didn't I mention that to you in email like a year ago? Right there under our noses in TBF all this time. I did calcs when I found that for M1A 11-twist and bearing surface of engraved (but not bumped-up) 30 sil. bullet, came up with around 10K psi on sides of lands at 2200 fps, way under 50/50 alloy strength. Pretty much settled what we and DrB were talking about way back....bullet ain't gonna strip unless it's made from linotype or similar that will literally abrade away at hv. Gotta have the right alloy for pressure/velocity which means not hard/bittle/flaky and not too much tin....like SOMEONE has been telling us for years.

Gear

Are you talking to talking to DougGuy as I don't know you??

[geargnasher]

Of course you know me. But no matter, this formula you posted settles a whole lot of questions about trailing edge failure and alloy failure. I didn't bring it up here when I found it because it contradicts popular opinion and everything Molly tried so hard to convince us of about velocity limits of cast bullets. This should be a great discussion if folks will read carefully and keep an open mind.

Gear

[DougGuy]

I hardly notice torque in my .308 and I use 180gr @ about 2400fps but I BIG TIME notice torque in a Vaquero with a Lee 300gr over a full house load of H110, as it turns the gun completely sideways in your hands regardless of how hard you fight against it. I just can't imagine the torque forces are in the thousands of ft lbs.

[geargnasher]

....but those ft/lbs torque are pulling on a "lever" only one bullet radius long...i.e. not much mechanical advantage.

Gear

[vzerone]

I redid the image, looks like the other one is there too. Oh well at least you can read it now.

[W.R.Buchanan]

Given the same velocity, the faster twist barrel will have more of a negative effect than the slower twist barrel,,, but only after the RPM Threshold for that "particular boolit" has been exceeded.

Below that point it's all about RPM's, and every Bullet/Boolit has a sweet spot for RPM's that it likes best. Once that speed has been exceeded it is probably is more about balance than actual damage to the Bullet/Boolit, and at this point accuracy could start to suffer.

Only under extreme circumstances would Boolit Damage due to excessive speed become a factor. In order to achieve such velocity the boolit would have to be pushed so hard that it would probably result in deformation of the base of the boolit. This is where the problems start, as we all know the rear end is the "steering end." Once again this is not due to rotational torque being applied, but base deformation due to high pressure.

At chamber pressures a bullet is essentially fluid as it is being shoved thru the bore. How fluid it is, depends on the pressure applied and the material the bullet is made from. They actually make steel bullets! I have the drawings for them in my shop! They go thru the barrel just fine as very little known to man can stop a 60,000psi kick in the butt. Even Water will go thru steel at 60,000 psi as witnessed by Water Jet Cutting Machines.

This is also why they invented Jacketed Bullets. They can absorb more pressure without deformation than lead boolits can. This results in Higher Velocities, Better Accuracy, Flatter Trajectories, and overall more useful Point Blank Range for a given Caliber/Cartridge/Weapons System... Still deformation of the base of a jacketed bullet has the same effect as it does on a lead boolit.

It upsets the rotational balance of the projectile as it travels down range.

I doubt that "rotational torque" would actually become a significant factor until the boolit actually stripped thru the rifling, and at that point the actual effect would be not enough rotation being transferred to the boolit, as opposed to too much rotation,,, thus resulting in instability.

I do not see being able to quantify this mathematically as being a useful tool. You can just work the bullet's speed up until the accuracy goes away, back off, and achieve an exact result as opposed to a theoretical result,,, which you still have to prove by practical application.

My .02

Randy

[vzerone]

Forget about the torque applied to the rifle from the bullet. I'm concerned with the force of the bullet against the rifling. I want to know if this force is high enough to damage the bullet that's it's accuracy deteriorates. Say that it does when you're pushing it very hard such as in high velocity. What exactly does it change? After all the bullet is confined in the bore.....what changes? I tried pushing pure lead bullets in various caliber trying on purpose to get the bullet to strip and I mean strip entirely. Unfortunately I only examined the bore after firing as I couldn't recover the bullet undamages (especially being pure lead). Say it did strip, wouldn't the grooves be filled with lead? There was no evidence of that. In fact I was surprised that the bore looked rather good. If someone could nail exactly what changing on the bullet then we can work on trying to alleviating that. Then I question myself that whatever happens to the bullet in the bore only show's up after exiting the bore.

[W.R.Buchanan]

If the boolit is plain based then when you drive it hard enough to strip the rifling you have also deformed the base. The combination of the two kills accuracy. But as you slow down to where you aren't stripping the rifling you still are deforming the base of the boolit because you are still above the threshold of Training Edge Failure.

As the base melts away blow by will occur, and thus barrel leading. In the case of stripped rifling the excess metal stripped off the boolit is blown out the end with the rest of the boolit,,, just not in one piece. Or since the groves are only .004-.005 deep on a side the boolit is probably just being swaged to bore size as opposed to having that material cut from the outside.

This is why you can't get any accuracy from a plain based boolit beyond 1500-1600 fps. The combination of Friction caused by Speed and Heat from the charge is deforming the base of the boolit. IE; Tailing Edge Failure.

Randy

[vzerone]

I don't believe in a cast bullet being fluid or even in the elastic/plastic state while in the bore. If it really was in a true fluid state the gas would blow it out of the barrel as an alloy spray of liquid. I also don't believe if it was in any of those states that when it leaves the barrel that it changes back to the state it was before you shot it and maintain the accuracy that it does. It only has microseconds upon ejection from the muzzle to change back and there are a lot of negative influences on it that would literally explode it near the muzzle and that's just not happening.

I don't believe in a sweet spot either. If a bullet is truly perfect the rotation of it doesn't affect it. There are too many motors and other apparatuses out there that have a spinning shaft that have mind boggling rpm. It's damn near impossible, for a bullet that is already spinning in the barrel, to make the transition from the barrel to the atmosphere with absolutely nothing changing. Most often the change that does happen is restabilized by the gyroscopic action of the bullet spinning. That action will fight hard to keep the bullet on it's path. I have fired bullets way beyond what they should have been going, and yes they key holed, but the interesting thing is they still printed a 2.5 to 3 inch group on the target....although not in the same area of the target that the same bullet printed it's group when it was stabilized.

[geargnasher]

Land pressure alone won't strip an engraved bullet...but abrasion from rubbing hard, brittle alloy across the leading edge of the rifling at HV with brittle alloy can erode enough to strip...plus once wear starts the gap, gas will blast by on the trailing edge and start chewing it away from the back side.

I think this is the whole reason that 10 twist .30 cals don't shoot good HV groups with Linotype but work great with 50/50 alloy and the exact right pressure curve.

Gear

[Ballistics in Scotland]

The area of the rear of a .257 bullet is 0.051875 of a square inch. Is there some way 50,000psi can exert a force of more than about 2500 pounds? Some of that is diverted into overcoming friction, but the greater part is devoted to driving the bullet forwards.ere

A point in danger of being dwarfed by the above very large one is that sliding friction varies in proportion to the force pressing two surfaces together, and with the coefficient of friction specific to that combination of materials. But in theory it doesn't vary at all with the area in contact. If a one-ton sledge is short, it will have more weight per square inch of runners, and thus the same one-ton force pressing on the ground.

This isn't perfectly true in practice. A short sledge will have its motion translated into more pitching and tossing as it encounters small inclines and obstructions in its way. But it will be very close to true with a normal bullet and smooth barrel surface. The number and depth of grooves makes very little difference. The rifling pitch will make some, however.

[W.R.Buchanan]

There are varying degrees of "Fluidity." Glass is a fluid. Believe me bullets no matter what they are made from are fluid when the pass thru a barrel. If they weren't they couldn't be engraved by the rifling. If the rifling was simply shearing the material off the bullet then there would be chips leftover. The excess metal is being swaged into a different form and the displaced metal is simply moved to a different position on the bullet.

Metal chips which result from being cut off a bigger piece are fluid when they separate from the piece being machined. Sometimes they stick to the cutting tool much like lead sticks to a barrel. Lubrication and cooling offset this effect, same as in a barrel.

A bullet traveling thru a barrel is undergoing a "Swaging Process." and a Swaging Process relies on Fluidity of the material in order to happen.

Next:

All entities have a "Resonance Frequency" and once that frequency is amplified past a certain level,,, that entity explodes.

However below that point, The ability of the entity to tolerate lesser forces are products of materials and design and speed of movement. Also those forces do influence the entity greatly, they just don't allow it to blow up.

In other words before destruction happens, the harmonic frequency ranges that are generated by the entities movement are being tolerated. But they can make it go stupid.

There is no such thing as 100% perfect balance. Perfection is unobtainable. Bullets are very close but they are not perfect. If they were perfect then rotational speed would not affect them. However it does affect them and the reason why is the vibration caused by the speed of rotation and the amount of "out of balance" present.

But the actual force involved here that is causing the bullet to deviate from it's intended path is "Centrifugal Force," and that force is acting on the out of balance factor of the rotating entity.

If there was no out of balance factor present IE: perfect balance,,, then the only thing Centrifugal Force could affect would be the "surface tension" of the material being spun. Once that was exceeded, the entity would explode.

As long as that speed of rotation was not exceeded, the entity would continue on it's intended path only being influenced by gravity.


The sweet spot referred to above includes the design of the bullet as well as material and can only be expressed as a range since it is impossible to exactly quantify all the factors of the materials composition that would affect the percentage of out of balance inherent within that one bullet or group of bullets/boolits. Thus a range is given which has proven to be successful to varying degrees.

There are no absolutes!

It effectively is an average of all those factors which nobody cares about, because that level of Minutia does not have enough of an influence on performance to alter the effectiveness of that bullet for it's intended purpose.

It is possible for an individual to make something work without completely understanding how or why it works. It would be nice to understand exactly all that contributes to the function of something, however there are so many things out there to figure out that a person might not actually get much done in a lifetime, or two.

Unfortunately there is no one answer to everything. People have been looking for it since the beginning of time, nobody's got close.

What I have found successful is a good basic understanding of what I'm doing which gives me the ability to accomplish my goal for that thing. That knowledge often translates to other disciplines and can have a logarithmic effect. IE: the more you know the better off you are. :veryconfu

See my signature below.

Randy

[Ballistics in Scotland]

Download The bullet's Flight by F.W. Mann from Castpics and read the whole section that page is from, it gives a full explanation of how the formulas was derived with consideration to certain parts of the equation which make it not precisely accurate but so nearly so as to be inconsequential for our purposes.

It also explains that a cast bullet is somewhat plastic under at least the first impact of maximum pressure, although of course nowhere near liquid. That is why a fairly soft alloy should upset to seal the bore, when a very hard one may not, and as a result will lead more. Only it shouldn't deform much. There may be some bluntening of the nose shape, and this is probably the reason why cast bullets often don't give good accuracy with the sort of sharp point which works with jacketed. Upsetting of the nose is likely to be assmmetrical, and although it isn't as important to accuracy as the base, it isn't negligible.

[vzerone]

Randy,

The point I was coming from is that many on this forum believe the bullet is near being in liquid state or more correctly that it is in a soft putty state. You're coming from the engineering aspects in which you are correct. Everything in the our world that rotates does have a limit or it explodes or becomes dangerous.

Those stripping test I performed where done with a large white paper sheet so many feet in front of the barrel and there was no lead holes that showed up on that paper other then the bullet hole. I just don't believe a rifle bullet will strip totally.

[vzerone]

The area of the rear of a .257 bullet is 0.051875 of a square inch. Is there some way 50,000psi can exert a force of more than about 2500 pounds? Some of that is diverted into overcoming friction, but the greater part is devoted to driving the bullet forwards.ere

A point in danger of being dwarfed by the above very large one is that sliding friction varies in proportion to the force pressing two surfaces together, and with the coefficient of friction specific to that combination of materials. But in theory it doesn't vary at all with the area in contact. If a one-ton sledge is short, it will have more weight per square inch of runners, and thus the same one-ton force pressing on the ground.

This isn't perfectly true in practice. A short sledge will have its motion translated into more pitching and tossing as it encounters small inclines and obstructions in its way. But it will be very close to true with a normal bullet and smooth barrel surface. The number and depth of grooves makes very little difference. The rifling pitch will make some, however.

BIS, it does too matter how many rifling grooves there are and their depth. I have a friend that manufacturers 6.8 Rem AR's. He has exceeded everyone else velocities by a whopping figure and safely. He does it by going to a slower twist, three groove rifling, and different groove depth.

[vzerone]

It also explains that a cast bullet is somewhat plastic under at least the first impact of maximum pressure, although of course nowhere near liquid. That is why a fairly soft alloy should upset to seal the bore, when a very hard one may not, and as a result will lead more. Only it shouldn't deform much. There may be some bluntening of the nose shape, and this is probably the reason why cast bullets often don't give good accuracy with the sort of sharp point which works with jacketed. Upsetting of the nose is likely to be assmmetrical, and although it isn't as important to accuracy as the base, it isn't negligible.


You're talking the plastic stage more in the sense of swaging, not as soft puddy because that doesn't happen. I also don't believe in nose slump.

[geargnasher]

Ok, NOW I get why you've always said you don't believe in "putty" bullets, it's only a matter of semantics. Metal does flow to a degree, ce can all agree on that. I still argue that noses can and do slump, but again semantics...metal flows up from the base and can swell up the nose a little if you bump them hard enough from behind. Some would call this 'setback' from the nose's static inertia, but i don't really think that's the best description of how "slumped" noses occur. IIRC Bob has recovered many bullets with varying degrees of "slump" to the noses depending on powder and alloy, mild slump always started at the base of the nose, filling out into the grooves and progressed forward with hotter loads....not from the nose point back...leading to the postulation that the displaced metal came from behind (plus he indicated that the laws of Fluid Dynamics say that will happen, too).

Gear

[44MAG#1]

" Vaquero with a Lee 300gr over a full house load of H110, as it turns the gun completely sideways in your hands regardless of how hard you fight against it. I just can't imagine the torque forces are in the thousands of ft lbs."

I have shot 300 grain full tilt loads in a 45 Colt and 44 Mag Nd I have NEVER had a gun turn completely sideways in my hand EVER.
I sure would like to see a video of that happening. Not saying it can't. But it is one of those things I sure would like to see.
Ive shot short barrels and longer barreled handguns and still haven't had that happen.
I would like to experience that just one time.

[vzerone]

Ok, NOW I get why you've always said you don't believe in "putty" bullets, it's only a matter of semantics. Metal does flow to a degree, ce can all agree on that. I still argue that noses can and do slump, but again semantics...metal flows up from the base and can swell up the nose a little if you bump them hard enough from behind. Some would call this 'setback' from the nose's static inertia, but i don't really think that's the best description of how "slumped" noses occur. IIRC Bob has recovered many bullets with varying degrees of "slump" to the noses depending on powder and alloy, mild slump always started at the base of the nose, filling out into the grooves and progressed forward with hotter loads....not from the nose point back...leading to the postulation that the displaced metal came from behind (plus he indicated that the laws of Fluid Dynamics say that will happen, too).

Gear

This is how I see slump. You take some kid's clay and you roll out a long cylinder of it. They you stand it upright on a table. So it leans over and "slumps". That's how I take the description. A bullet nose doesn't do that. When pressure hits the base of the bullet it starts to swage it, make the bullet obturate to the bore. How far this effect travels through the length of the bullet is dependent on the alloy and the pressure. You can't move metal without it going somewhere else. If there is enough pressure to reach close to the nose well then that metal you've displaced from the rear is going to change the nose.

I'm not quite certain about setback. I see setback as the stationary bullets suddenly accelerates at a tremendous speed instantly. That doesn't happen. I only can interpret stuff like with the speed of light acceleration.

[popper]

Vzerone - your numbers are WAY off. 55k psi on a 257 ( .051 sq. ") = 2805# on the base. For 30 cal 1:10 6 groove I calculate 35K psi of which 2473# on the base, 412# total groove, 378# axial, 35 radial#. It's the 378# axial IMPULSE that does the damage. That force does generate a substantial torque on the pistol grip (rifle or pistol). Reminds me of the EMDrive bandied about - supposedly defeats Newtonian physics. Ha, pushing narrow beam radio waves out at S.O.L. does generate momentum. Supposed to reduce fuel weight of spacecraft but where do you get the Magnetron power? It's about efficiency.

[vzerone]

" Vaquero with a Lee 300gr over a full house load of H110, as it turns the gun completely sideways in your hands regardless of how hard you fight against it. I just can't imagine the torque forces are in the thousands of ft lbs."

I have shot 300 grain full tilt loads in a 45 Colt and 44 Mag Nd I have NEVER had a gun turn completely sideways in my hand EVER.
I sure would like to see a video of that happening. Not saying it can't. But it is one of those things I sure would like to see.
Ive shot short barrels and longer barreled handguns and still haven't had that happen.
I would like to experience that just one time.

They are in that pound range, it's just they are pushing only the total area of the all the lands and the bearing length of the bullet. Look at the relationship of your rifle recoil when you consider the muzzle energy in foot pounds. The recoil doesn't even make 100 foot pounds.

As I mentioned before there is a formula to change your rifle, or handgun, torque force in foot pounds, but it's in decimal place. I'll try dig that up.

[Ballistics in Scotland]

The reduced twist should produce a certain amount of increased velocity for a given pressure, if it will stabilize the bullet it is desired to use. But how many of the major after-market barrelmakers prefer three grooves?

[vzerone]

The reduced twist should produce a certain amount of increased velocity for a given pressure, if it will stabilize the bullet it is desired to use. But how many of the major after-market barrelmakers prefer three grooves?

Interesting you ask that. Lilja, as you will make you what you want. A while back a gentleman was shooting some 6mm cartridge, something like the 6mmPPC and he had a request of Lilja for a barrel of a certain twist and certain number grooves. The grooves were 3. Lilja thought it was kind of strange, but he made the barrel. Then he made himself one to test and was very surprised that it did what the gentleman said it would, with the accuracy. He now catalogs three groove barrels.

[shooter93]

I don't know if you'd call it slump or deformation but somewhere around here I have a picture from Speer labs. Years ago you could call these guys with all kinds of questions and they were very cordial....anyway....the picture shows a spire point jacketed bullet going down a barrel and the nose is pushed into a round nose/flat point style. Their research into this was used to design their jacketed bullets of course but if a jacketed bullet goes through this kind of transformation I have no doubt a cast lead one will more easily with less pressures.

[geargnasher]

This is how I see slump. You take some kid's clay and you roll out a long cylinder of it. They you stand it upright on a table. So it leans over and "slumps". That's how I take the description. A bullet nose doesn't do that. When pressure hits the base of the bullet it starts to swage it, make the bullet obturate to the bore. How far this effect travels through the length of the bullet is dependent on the alloy and the pressure. You can't move metal without it going somewhere else. If there is enough pressure to reach close to the nose well then that metal you've displaced from the rear is going to change the nose.

I'm not quite certain about setback. I see setback as the stationary bullets suddenly accelerates at a tremendous speed instantly. That doesn't happen. I only can interpret stuff like with the speed of light acceleration.

We're on the same "page" with all that.

Gear

[longbow]

I have recovered cast boolits shot from my Lee Enfield with 1:10" twist that showed signs of stripping in that the grooves in the boolit were wider than the lands yet the rifling has equal width lands and grooves.

When this happens there is an opening for gas leakage which subsequently causes gas cutting which further damages the boolit. I found that oven heat treating for the same boolit and load solved the issue.

I have also recovered .303 boolits (Lyman 31141 170. flat point) shot into soft deep snow over stout loads and no gas check on them. There was no sign whatsoever of rifling on recovered boolits. Whether the rifling stripped or gas cutting removed the grooves, or a combination, I can't say but it certainly happened.

You can believe what you want but lead is elastic/plastic to some degree as is steel and everything else "solid" around you.

I have not done the calculations to compare chamber pressure to the pressures developed during boolit swaging but let me ask how lead is swaged into boolits if it is solid and can't flow? How do boolit bases "bump up" which they do. In fact BP PP cartridge shooters depend on the boolit bumping up to fill the grooves as most people patch to bore diameter. If the lead didn't flow it wouldn't bump up.

So let's say you have a cast boolit that has 8,000 PSI yield strength and you put it in a closed cylinder and subject it to 50,000 PSI? Do you think it will look the same when removed? I'm going to go out on a limb and say you will get a shorter fatter cylinder with no visible lube grooves and flat nose.

Even if a boolit is filling the barrel completely it can still flow ~ think of collapsed lube grooves. It can also increase in length which is what would happen during stripping ~ the lead is extruding.

Yes, the lead will flow when the pressure on the lead exceeds it's yield strength. The strongest lead alloy you will find runs about 12,500 PSI after heat treating but most chamber pressures exceed that even in handguns. Almost any boolit you shoot will have less strength than that.

Also, it is not velocity but acceleration that results in the torque you feel. The boolit does not particularly want to accelerate down the barrel nor does it want to rotate. Both require significant energy which is generated by the gas pressure on the boolit. As the boolit accelerates it is forced to rotate by the rifling and the attendant reactions are reward recoil of the gun and rotational torque generated by the accelerating boolit.

As for nose slump, it all depends on stress. If the stress in the nose of the boolit exceeds its yield strength the material will yield. That stress is due to the acceleration of the boolit and the mass being accelerated. At the base of the boolit you have the entire weight ahead being pushed at the tip of the nose you have nothing but air being pushed. Everywhere in between sees a stress gradient.

A boolit with a long unsupported nose can certainly slump if accelerated at a high enough rate. Again, let's look at BP PP boolits and how they bump up along the body. That bump up will stop where the stress from acceleration is less than the yield strength of the alloy.

Longbow

[Ballistics in Scotland]

Also, it is not velocity but acceleration that results in the torque you feel. The boolit does not particularly want to accelerate down the barrel nor does it want to rotate. Both require significant energy which is generated by the gas pressure on the boolit. As the boolit accelerates it is forced to rotate by the rifling and the attendant reactions are reward recoil of the gun and rotational torque generated by the accelerating boolit.

Torque is a rotational force, and the acceleration results from the force, rather than the other way around. Acceleration is proportional to that force, so as we probably all know a firearm a hundred times the weight of the bullet accelerates a hundredth as much, and achieves a hundredth of the velocity by the time they part company.

Fewer people realize that the same thing applies to rotational acceleration. A firearm a hundred times the weight of the bullet will have a hundredth the tendency to rotate. It is unlikely to be noticeable. If it was, we would hear more of one direction of twist being superior to another.

[longbow]

First, I apologize to vzerone. I am not trying to be argumentative and I had missed or misread some of his comments, then saw them when I reread. My brain is a little addled by cough medicine currently so I guess I focused on a few of the comments and missed others. Sorry about that.

As for torque being a rotational force, absolutely! The boolit is put into motion by the gas pressure acting on its base resulting in a force. The force causes the boolit to accelerate down the barrel. The rifling causes the boolit to rotate which results in a reaction of the gun in the opposite direction. That reaction of the gun is caused by the rotational inertia of the boolit as it is accelerated radially by the rifling just as rearward recoil is an opposite reaction to the boolit accelerating up the barrel.

The rearward recoil is far more noticeable than the rotational reaction for just the reasons you mention, though I think it is noticeable when I compare my Lee Enfields with left hand twist to my other rifles with right hand twist. Not a lot but noticeable.

Longbow

[vzerone]

First, I apologize to vzerone. I am not trying to be argumentative and I had missed or misread some of his comments, then saw them when I reread. My brain is a little addled by cough medicine currently so I guess I focused on a few of the comments and missed others. Sorry about that.

As for torque being a rotational force, absolutely! The boolit is put into motion by the gas pressure acting on its base resulting in a force. The force causes the boolit to accelerate down the barrel. The rifling causes the boolit to rotate which results in a reaction of the gun in the opposite direction. That reaction of the gun is caused by the rotational inertia of the boolit as it is accelerated radially by the rifling just as rearward recoil is an opposite reaction to the boolit accelerating up the barrel.

The rearward recoil is far more noticeable than the rotational reaction for just the reasons you mention, though I think it is noticeable when I compare my Lee Enfields with left hand twist to my other rifles with right hand twist. Not a lot but noticeable.

Longbow

Longbow,

No need for any apology, you didn't do anything wrong in my eyes. It's hard to try to figure something out that is very difficult to view. All the things that this rifling torque puts on a cast bullet, especially when fired from a very fast twist, all seems to be negated in a paper patch bullet. It's hard to believe that those thin wraps of paper prevent all this from happening to the core of the PP bullet even with it's near pure lead. I know that paper is much tougher then we imagine. We're all use to tearing it with our hands easily. Never the lest the rifle groove, particularly deeper groove, cut grooves in the core as you can examine them from recovered PP bullets that aren't damaged excessively. So that core it getting the torque too, the paper is just sandwiched between that core and the rifling. The paper protects it enough that when firing a naked cast bullet under the same high velocity and high pressure wrecks it, easily.

[Ballistics in Scotland]

At one time the Great shooters of a bygone era south of you believed that a left hand twist countered a right hand shooters pulling to the right....
Funny how times change as new evidence comes to light. I figure that you are very versed in this aspect of thought from years ago.
Your thoughts of the weight of the rifle versus the weight of the bullet ability to torque the rifle I share your thoughts.

Ah, if you mean the land Scotland decided overwhelmingly by referendum not to give independence last year, it wasn't a matter of the shooter pooling to the right. There are two kinds of bullet drift at long range.

Ordinary drift, caused by gyroscopic precession, is almost neligible for most of us, and does indeed depend on the rifling twist.

Drift caused by the Coriolis effect, is actually totally negligible for those of us who don't want to hit a battleship at 20,000 yards, and its direction depends on whether you are north or south of the equator, but not at all on the direction of the rifling twist, and only a small fraction of negligible on the compass point towards which you are pointing the rifle.

The British decided that the next large war was almost certain to be fought in the Northern Hemisphere, and gave the Lee rifles a left-hand twist so that these two forms of drift would go some way towards cancelling each other out, instead of being cumulative. Well so they do, except that nobody is ever likely to notice. Of course it was in South Africa that they promptly fought the only large war in history in which ranges were long and the rifle was the dominant weapon. It was still just as good a rifling twist as anybody else's.

[44man]

I feel torque with my big bore revolvers. It is violent enough to spin a revolver under a scope or red dot. It also hurts my wrist. A .500 S&W will twist enough to spin the cylinder backwards to the first chamber.
Torque from the gun is also counter acting force on the boolit.
I recover boolits, PB by the way that show a lot of skid up front but it stops at the base band so I have a seal there. I get extreme accuracy so it has no affect.
My BFR revolvers all have much faster twist rates then any others. Although they have more torque, no guns have shot as good. Gun movement absorbs much.
When the boolit hits rifling it will torque the gun and there will be some balance to the pressure of impact. How can you measure it? It is a fools errand.
Might be why a Ransom rest can't equal a hand shot gun because it limits torque.
Boolit bases do not melt and lead does not flow from heat. Pressure is the force so you must contain it. Some use a GC to protect the base but you don't understand what they do. They are not to prevent melting, they stop skid so gas does not escape.
How could you measure rifling impact when the gun is twisting the other way? It would be like saying a boolit hits game harder then the recoil on your hand or shoulder.
I love the old movies where a jerk is blown back 20'. Of the hundreds of deer I have dropped none have been blown anywhere, they drop because they are DEAD or the CNS was hit.
I have read crazy stuff like more spin will kill faster so why doesn't a deer spin when hit? Killing is from the bullet/boolit, not twist or ME or anything felt by shooting.
Even a .22 will twist the gun so how would you measure anything? Lock the gun in a vise?

[44man]

Not talking drift from spin of course. Just impact on rifling. So if the gun twists with impact. Does in negate the impact? The gun is heavier so it can't take it all up so the boolit WILL skid some. Where you stop skid is what is important.
A harder jacket helps but you can do it with lead too.
The crux of the matter is, the more the gun twists, the less impact you will have on impact to rifling.
Do not have to be a rocket scientist to see it with pages of figures. Just takes a shooter that can think.

[44man]

Sorry, no cigar there. Newton's laws still apply.
That means if you reach out and catch the apple it will not slow down!
Gravity increases speed at 32 fps per second until max is reached and no more is attained. So you say it can not be interrupted.
Max has no answer because of air resistance and weight or size of an object falling. There are formulas for each. Actually there is no limit to speed attained without outside interference.
Gravity is not pushing boolits out. It only effects the boolit path after barrel exit. Sorry the gun weight and counter force does affect boolit impact to rifling.
How do you get newton's theory to explain a boolit?

[44man]

Newton's Third Law

Newton's Third Law
Identifying Action and Reaction Force Pairs (http://www.physicsclassroom.com/class/newtlaws/Lesson-4/Identifying-Action-and-Reaction-Force-Pairs)



A force is a push or a pull that acts upon an object as a results of its interaction with another object. Forces result from interactions! As discussed in Lesson 2 (http://www.physicsclassroom.com/Class/newtlaws/u2l2a.cfm#top), some forces result from contact interactions (normal, frictional, tensional, and applied forces are examples of contact forces) and other forces are the result of action-at-a-distance interactions (gravitational, electrical, and magnetic forces). According to Newton, whenever objects A and B interact with each other, they exert forces upon each other. When you sit in your chair, your body exerts a downward force on the chair and the chair exerts an upward force on your body. There are two forces resulting from this interaction - a force on the chair and a force on your body. These two forces are called action and reaction forces and are the subject of Newton's third law of motion. Formally stated, Newton's third law is:

For every action, there is an equal and opposite reaction. http://www.physicsclassroom.com/Class/newtlaws/u2l4a2.gifThe statement means that in every interaction, there is a pair of forces acting on the two interacting objects. The size of the forces on the first object equals the size of the force on the second object. The direction of the force on the first object is opposite to the direction of the force on the second object. Forces always come in pairs - equal and opposite action-reaction force pairs.


Examples of Interaction Force Pairs A variety of action-reaction force pairs are evident in nature. Consider the propulsion of a fish through the water. A fish uses its fins to push water backwards. But a push on the water will only serve to accelerate the water. Since forces result from mutual interactions, the water must also be pushing the fish forwards, propelling the fish through the water. The size of the force on the water equals the size of the force on the fish; the direction of the force on the water (backwards) is opposite the direction of the force on the fish (forwards). For every action, there is an equal (in size) and opposite (in direction) reaction force. Action-reaction force pairs make it possible for fish to swim.
http://www.physicsclassroom.com/Class/newtlaws/u2l4a3.gifConsider the flying motion of birds. A bird flies by use of its wings. The wings of a bird push air downwards. Since forces result from mutual interactions, the air must also be pushing the bird upwards. The size of the force on the air equals the size of the force on the bird; the direction of the force on the air (downwards) is opposite the direction of the force on the bird (upwards). For every action, there is an equal (in size) and opposite (in direction) reaction. Action-reaction force pairs make it possible for birds to fly.
Consider the motion of a car on the way to school. A car is equipped with wheels that spin. As the wheels spin, they grip the road and push the road backwards. Since forces result from mutual interactions, the road must also be pushing the wheels forward. The size of the force on the road equals the size of the force on the wheels (or car); the direction of the force on the road (backwards) is opposite the direction of the force on the wheels (forwards). For every action, there is an equal (in size) and opposite (in direction) reaction. Action-reaction force pairs make it possible for cars to move along a roadway surface.
More!
The force on the rifle equals the force on the bullet. Yet, acceleration depends on both force and mass. The bullet has a greater acceleration due to the fact that it has a smaller mass. Remember: acceleration and mass are inversely proportional.
So mass of a boolit has a larger affect on the weight of the gun and will impart more force on the gun, (twist, recoil). Newton is correct, equal and opposite forces.
So you say the boolit hitting the rifling has no opposite force.

[W.R.Buchanan]

Randy,

The point I was coming from is that many on this forum believe the bullet is near being in liquid state or more correctly that it is in a soft putty state. You're coming from the engineering aspects in which you are correct. Everything in the our world that rotates does have a limit or it explodes or becomes dangerous.

Those stripping test I performed where done with a large white paper sheet so many feet in front of the barrel and there was no lead holes that showed up on that paper other then the bullet hole. I just don't believe a rifle bullet will strip totally.

At the point of firing, when the bullet starts to move it is in a Fluid state. As I said there are varying degrees of fluidity, and if the bullets shape changes, it is in a state of Fluidity.

The concept of true Polygonal Rifling relies on the fact that a Round Boolit alters it's shape to a polygon with round corners when it travels down the bore. If this boolit "stripped the rifling" there are no sharp edges to cut material from the boolit, thus it has to be swaged.

No matter what the material is only two things can happen as it travels down the barrel. Either it conforms to the barrels profile (Bullet Fluid), or the barrel conforms to the bullets profile. (Barrel Fluid) One way or another it is going thru the hole, and the only way the barrel would conform to the bullet is if the bullet is harder than the barrel.

I don't believe the material is cut from the bullet when it strips the rifling and your tests prove that. I would accept that it is swaged to "Bore Diameter" instead. If it was shearing the material off the bullet it would blow the chips out the end and your white paper would have shown that.

Randy

[runfiverun]

when I am swaging cores I have developed a technique to squeeze the excess core material out in a very even manner so that I get very good core weights.
if I just push the handle to the bottom of the stroke in a smooth even manner I do not get the sudden squirt of material out of the bleed-off hole, it tends to not flow as well and resists the pressure.
if however I get the core under pressure then use a quick motion to the handle to push the stem into place [creating a sudden smaller volume] rather abruptly I get a nice quick shot of core material out of the bleed-off hole.
this gives me more consistent weights because I am moving the internals of the core and flowing the material.

despite what many think about a lead boolit in a rifles barrel it does behave much the same way as swaging a boolit in a die reacts to pressure.
the same alloy's also act the same way under pressure and many will flow much better than others.

but that flow of material can be adjusted or even partially ignored by when and where the pressure is applied.
of course you will move material if it is jammed into a smaller hole.
moving it all evenly around that circle and giving it someplace to go will not make the boolit get longer it just moves the material from place A to place B [place B being the front wall of the lube groove if shaped properly]
and from place C. to place D. [the back of the last drive band] etc.

the lands are going to cut into the side of the boolit and this is the critical area everybody focuses on and the area they can do the least about.
except to try and minimize the damage.
how they choose to deal with minimizing that damage will naturally affect the outcome at the target.
some choose to deal with it by getting the material engraved gently and then accelerating and other choose to try a higher antimony bearing alloy forgetting antimony crystals breaks down under stress and pressure and actually allows the alloy to flow even easier [antimony is an internal lubricant to lead]
Tin,, NOW Tin is very good at resisting pressure and flex until it breaks and tears apart, it doesn't move and flow very well so it just gets shoved or torn around under a barrels stresses.

so we have all kinds of rotational forces, and pressure from behind, and friction, and then,,, suddenly it's all let go of somewhere in the barrel.
this is the other half of the equation everybody forgets about,,, that sudden drop off of pressure in the barrel and then the big one again at the muzzle.

[vzerone]

44man No,twisting of the gun (torque) does NOT lower the force on the rifling - which YOU stated - if I interpreted it correctly. Tired of hearing a lot of 'wives tales' stuff here. The formula first introduced here is COMPLETELY WRONG. Before the flaming starts, consider his fps theory and the real fps in the first inch of travel - when the force is applied to the rifling/boolit. Do a couple integration of pounds force to the base and get the real answer. Larry Gibson provided the pressure trace and I did the integration. As stated above, lead is not 'cut' by the rifling, just relocated. If it can't move before fracturing, it is 'stripped'.

That formula is not flawed. The pressure is calculated at peak pressure of peak velocity of the bullet in the barrel, not at the very beginning when it first enters the bore/rifling. It's up the barrel somewhere.

[vzerone]

Here's the formula for figuring how much force the rifle moves from the torque of the bullet applied to it via rifling:

In any case the equation to determine the amount of torque the moving bullet will apply to the gun is:

M = (1.7x10^-9 x W x R^2 x n )/T
M= torque in lb ft
W = bullet weight in grains
R = radius of bullet diameter in inches
n = RPM of bullet
T = time bullet is in barrel in seconds
I applied this to a 50 grain .22 caliber leaving barrel at 300000 RPM with a barrel time of 1 millisecond. I got .31 lb ft torque. Determining how much the gun will move before the bullet leaves could be figured but it depends on so many things that would be hard to pin down that I wonder if you could ever get close. For example, friction at the gun support would probably be very tough to predict.

It's very little as I said previously. Look at the rearward recoil of a rifle as compared to how much muzzle energy the bullet has. For example take the 460 W. Mag. It has tons of energy at the muzzle, but the force the recoil pushed the rifle against your shoulder doesn't even come near to 100 pounds alone tons.

I've edited to correct the formula:

The formula I gave you for time was wrong . What I should have said is: divide muzzle velocity by two and then divide the barrel length by this
For example 3025/2 = 1512 ft/sec then 28/12 /1512 = .0015 sec
(The 12 in last calculation converts inches to ft.)

[vzerone]

I feel torque with my big bore revolvers. It is violent enough to spin a revolver under a scope or red dot. It also hurts my wrist. A .500 S&W will twist enough to spin the cylinder backwards to the first chamber.
Torque from the gun is also counter acting force on the boolit.
I recover boolits, PB by the way that show a lot of skid up front but it stops at the base band so I have a seal there. I get extreme accuracy so it has no affect.
My BFR revolvers all have much faster twist rates then any others. Although they have more torque, no guns have shot as good. Gun movement absorbs much.
When the boolit hits rifling it will torque the gun and there will be some balance to the pressure of impact. How can you measure it? It is a fools errand.
Might be why a Ransom rest can't equal a hand shot gun because it limits torque.
Boolit bases do not melt and lead does not flow from heat. Pressure is the force so you must contain it. Some use a GC to protect the base but you don't understand what they do. They are not to prevent melting, they stop skid so gas does not escape.
How could you measure rifling impact when the gun is twisting the other way? It would be like saying a boolit hits game harder then the recoil on your hand or shoulder.
I love the old movies where a jerk is blown back 20'. Of the hundreds of deer I have dropped none have been blown anywhere, they drop because they are DEAD or the CNS was hit.
I have read crazy stuff like more spin will kill faster so why doesn't a deer spin when hit? Killing is from the bullet/boolit, not twist or ME or anything felt by shooting.
Even a .22 will twist the gun so how would you measure anything? Lock the gun in a vise?

I don't agree with a few things here. One is what the gas check does. It's not to stop skidding. Reading Mann's book can give you a very good clue as to what a gas check does. Yes he was working with flat base bullets. That sharp cornered base is very fragile not only from the beginning of it's travel down the barrel, but also at the very end of the barrel. If you say gas check grip the bullet to prevent skidding how do you explain that with the Lyman slip on checks and even worse the home made aluminum checks. Neither of those grip the bullet very well. That gas check is there to protect that fragile sharp cornered base from the hot powder gases, from the abrasion of the yet unburned powder kernels, and gas blow by. When I say protect from the hot powder gases I mean the pressure erosion from them not the melting. The heat is just not there long enough to actually melt the base.

I do agree with you that one can out shot a Ransom rest.

[44man]

Gas checks DO grip even if just easily applied. The engraving to the rifling tightens them.
It has never been proven the thin aluminum checks will work as good as the thick copper.
Larry should do a failure point on each.
It is a GAS CHECK, designed to keep grooves on the boolit at rifling size so gas does not leak.
Even PB shot over 55,000 psi shows no sign of melting or other damage from leakage at the base as long as rifling is taken. There will be powder blast pits on the base is all.
Most heat on a boolit is from friction in the bore or air, not from powder burn heat. Unless you shoot full auto, even brass is not that hot.

[44man]

More info.
Purpose High pressures, such as those commonly encountered in maximum loadings of magnum revolver (https://en.wikipedia.org/wiki/Revolver) cartridges or rifle (https://en.wikipedia.org/wiki/Rifle) cartridges, often result in significant problems when coupled with cast (https://en.wikipedia.org/wiki/Casting) or swaged lead bullets. It was long thought that the high temperatures melted the base of the bullet, but this is no longer thought to be the case. Instead, the high pressures allow propellant gas to escape past the bullet, causing gas cutting, which increases lead deposits in the barrel and unbalances the bullet. A gas check provides a thin layer of harder but still malleable (https://en.wikipedia.org/wiki/Malleable) metal on the base of the bullet that obturates (https://en.wikipedia.org/wiki/Obturate) to provide a seal and prevents the propellant gas leakage that causes gas cutting, and help the bullet grip the rifling (https://en.wikipedia.org/wiki/Rifling).[1] (https://en.wikipedia.org/wiki/Gas_check#cite_note-guntec-1)[3] (https://en.wikipedia.org/wiki/Gas_check#cite_note-nei-3) [4] (https://en.wikipedia.org/wiki/Gas_check#cite_note-taffin-4)[5] (https://en.wikipedia.org/wiki/Gas_check#cite_note-montana-5)[6] (https://en.wikipedia.org/wiki/Gas_check#cite_note-lasc-6)
While most cartridges operating at such high pressure use jacketed bullets, gas checked bullets are often less expensive, especially to a hand loader (https://en.wikipedia.org/wiki/Handloading) who can recycle (https://en.wikipedia.org/wiki/Recycle) lead to make cast bullets (https://en.wikipedia.org/wiki/Cast_bullet), and then must only pay for the gas check. Custom lead bullets, such as those for obsolete calibers, wildcat cartridges (https://en.wikipedia.org/wiki/Wildcat_cartridge), or for special purposes, are easily made with inexpensive casting or swaging equipment. In contrast, manufacturing jacketed bullets requires far more expensive equipment to draw the jackets and swage in the core, so is generally limited to commercial ammunition producers. As a result, although it is possible for hobbyists to manufacture jacketed bullets, many of them take the easier option and use gas checked bullets instead.[2] (https://en.wikipedia.org/wiki/Gas_check#cite_note-corbin-2)

[44man]

I figured this long ago without this information and is why I wonder about tin can checks doing as good.

[W.R.Buchanan]

One thing to consider is that a gas check applied to the back of a boolit will in effect create a "new base" on that boolit at the point of firing. IE the base of the boolit conforms to the interior shape of the gas check when the check is rammed into the base of the boolit at 15 to 35,000 psi. Lead will extrude from the bleed hole in a swaging die with considerably less pressure than that,,, so it would extend that the base of the boolit will conform to the interior shape of the gas check as it starts to move, as pressure builds to a point above that required to reform the lead base. IE; Swaging Pressure.

The rifling will in fact further crimp the check in place but after the boolit leaves the barrel Centrifugal Force may unseat it.

Some Gas Checks stay on, and some don't,,, we all can agree on that?

One other way to look at the Fluidity of a Lead Boolit is to compare being fired with being swaged in a blind hole die. Or being fired into a blind hole. As long as the pressure can be contained the boolit will take the shape of whatever the cavity looks like. In that case you are exchanging hydraulic force for firing force but pressure is pressure only the speed of application of that pressure changes.

When being fired in a normal barrel the boolit's base is seeing the Pressure being generated by the charge. if that pressure is above the pressure needed to swage that material then the base is going to be altered to some degree. Gas Check or not, the Base of that Boolit is still seeing the same pressure. In the case of the Gas Check it is simply shielding the material from the heat but it is not shielding it from the pressure, it is transmitting the pressure. It also helps to seal the bore so blow by doesn't have as much effect, and any lead that is melted in front of the Gas Check is scraped off as the Check passes by.

2 more cents.

Randy

[vzerone]

One thing to consider is that a gas check applied to the back of a boolit will in effect create a "new base" on that boolit at the point of firing. IE the base of the boolit conforms to the interior shape of the gas check when the check is rammed into the base of the boolit at 15 to 35,000 psi. Lead will extrude from the bleed hole in a swaging die with considerably less pressure than that,,, so it would extend that the base of the boolit will conform to the interior shape of the gas check as it starts to move, as pressure builds to a point above that required to reform the lead base. IE; Swaging Pressure.

The rifling will in fact further crimp the check in place but after the boolit leaves the barrel Centrifugal Force may unseat it.

Some Gas Checks stay on, and some don't,,, we all can agree on that?

One other way to look at the Fluidity of a Lead Boolit is to compare being fired with being swaged in a blind hole die. Or being fired into a blind hole. As long as the pressure can be contained the boolit will take the shape of whatever the cavity looks like. In that case you are exchanging hydraulic force for firing force but pressure is pressure only the speed of application of that pressure changes.

When being fired in a normal barrel the boolit's base is seeing the Pressure being generated by the charge. if that pressure is above the pressure needed to swage that material then the base is going to be altered to some degree. Gas Check or not, the Base of that Boolit is still seeing the same pressure. In the case of the Gas Check it is simply shielding the material from the heat but it is not shielding it from the pressure, it is transmitting the pressure. It also helps to seal the bore so blow by doesn't have as much effect, and any lead that is melted in front of the Gas Check is scraped off as the Check passes by.

2 more cents.

Randy

W.R.

Yes we can agree that some gas checks stay and other come off somewhere out from the muzzle.

I also can agree on the bullet is getting swaged by the gas pressure, but unlike a swaging die it's one, no getting formed the shape of swage die because it's not in one, and two. as the gas is pushing on it, it has somewhere to go...that is down the barrel. So with that respect I don't "think" the whole bullet is getting swaged. We can prove that by recovering cast rifle bullets that are undamaged and see how far toward their noses they were "bumped up" or obturated.

We need to get past what we're talking about currently and focus on what does rifling do to decrease the accuracy of a cast bullet when it's either pushed very hard or the rifling twist is very fast. If it's started straight into the bore and the bullet is of good quality meaning dang near perfect with no voids (we weigh them for that reason) what is changed on the bullet inside the bore?

[melloairman]

I am reading and learning a lot from each of you . All I can say is I shoot air rifles . My Korean rifles will only except a 10 -12 bhn alloy and maintain accuracy . With a chamber pressure of 3000 psi. not 30,000 psi and really no hot gas. The barrels are 1in 16 twist wide land narrow shallow grooves . Stripping occurs with a harder alloy and accuracy goes away . Marvin

[vzerone]

I am reading and learning a lot from each of you . All I can say is I shoot air rifles . My Korean rifles will only except a 10 -12 bhn alloy and maintain accuracy . With a chamber pressure of 3000 psi. not 30,000 psi and really no hot gas. The barrels are 1in 16 twist wide land narrow shallow grooves . Stripping occurs with a harder alloy and accuracy goes away . Marvin

That's sounds like the harder pellets aren't obturating and catching the rifling good. Makes sense. One of my pet ideas is for "someone" to make an air rifle where the pressure is equal to powder cartridge rifles just to see if the bullets fair any better on their trip up the barrel with no hot gases behind them. How high a pressure can air be compressed too?

[melloairman]

That's sounds like the harder pellets aren't obturating and catching the rifling good. Makes sense. One of my pet ideas is for "someone" to make an air rifle where the pressure is equal to powder cartridge rifles just to see if the bullets fair any better on their trip up the barrel with no hot gases behind them. How high a pressure can air be compressed too?
My psi would have to more than double for obtuation to take place even with pure lead . I have been told that air can not move fast enough to equal what powder gas can do . Even helium has its limits . I do not have all the answers to why this occurs but obturation is not the problem . Accuracy and fps both fall of at the same time . There are some readings with a Korean .357 rifle .
http://i301.photobucket.com/albums/nn55/melloroadman/RECLUSE/IMG_7250-RECLUSE11-23-12.jpg (http://s301.photobucket.com/user/melloroadman/media/RECLUSE/IMG_7250-RECLUSE11-23-12.jpg.html)
And here are some readings with a US made .357 with what is called a micro land barrel . Wide groove very narrow land but retains accuracy and energy.Marvin
http://i301.photobucket.com/albums/nn55/melloroadman/BHN%20COMPARISONS/IMG_6894a.jpg (http://s301.photobucket.com/user/melloroadman/media/BHN%20COMPARISONS/IMG_6894a.jpg.html)

[runfiverun]

maybe it wouldn't have to be that high.
remember that punching lead all at one time quickly generates a different reaction than accelerating it continuously.

[vzerone]

My psi would have to more than double for obtuation to take place even with pure lead . I have been told that air can not move fast enough to equal what powder gas can do . Even helium has its limits . I do not have all the answers to why this occurs but obturation is not the problem . Accuracy and fps both fall of at the same time . There are some readings with a Korean .357 rifle .
http://i301.photobucket.com/albums/nn55/melloroadman/RECLUSE/IMG_7250-RECLUSE11-23-12.jpg (http://s301.photobucket.com/user/melloroadman/media/RECLUSE/IMG_7250-RECLUSE11-23-12.jpg.html)
And here are some readings with a US made .357 with what is called a micro land barrel . Wide groove very narrow land but retains accuracy and energy.Marvin
http://i301.photobucket.com/albums/nn55/melloroadman/BHN%20COMPARISONS/IMG_6894a.jpg (http://s301.photobucket.com/user/melloroadman/media/BHN%20COMPARISONS/IMG_6894a.jpg.html)

Well you know high explosives are rated by their velocity I believe. So when gunpowder is confined it "sorta" an explosive and thus the gas moves faster then compressed air.

[melloairman]

maybe it wouldn't have to be that high.
remember that punching lead all at one time quickly generates a different reaction than accelerating it continuously.
He stated psi the same . The highest I have heard of is about 4,700 psi . There are AR that produce much more energy than these . But the results are the same . And with the constant push when the energy is up you can fill the twist of the rifle . Marvin

[vzerone]

But they DON'T occur at the same time. The 'torque' as you call it is dynamic. You cannot calculate it with a simple algebraic equation, thus your equation is flawed. Once the boolit starts spinning (rotating inertia) , the twist forces are reduced - as is the axial force (chamber pressure) on the boolit. Look at any recovered boolit, skidding occurs at the front band, usually none at the back.
Air rifles are constrained by the mechanics of the action (venturi), much slower than combustion of powder. I would expect them to act more like b.p. rifles.

If man can build spacecrafts, if man can land a man on the moon and get him back, if man can land various rovers on mars and have pictures sent back.....man can very well figure out the torque on a bullet or the pressure the bullet is pressed against the land walls. Let's quit arguing about the formula and whether it can be predicted or not. The original question I asked is what is happening to the bullet to damage it or make it so that it can't achieve good accuracy at high velocity from a fast twist barrel. I think it's agreed upon if the bullet is perfect, started straight, that the rpm has no affect on it once it's in flight. Of course we know perfect is a pretty broad term.

[MBTcustom]

Just a thought.
Everyone assumes the bullet gets "damaged" by the rifling and tries to make the science match that assumption. I do not believe this to be true. I have seen no evidence of it at all. The only damage I have seen was where the bullet stripped the rifling, but even that was done in a very consistent way around the bullet.
I do not believe the accuracy loss at HV is caused by bullet damage at all. I have a different, and very unpopular theory that squares with all the evidence of what was seen with the XCB project by those who contributed, by the paper patchers, and the fellows shooting sabots and copper jackets.


I think the bullet is releasing internal stress in flight because tough/hard alloys have enough strength to return to shape after being torqued.
The paper patch, sabot, and copper jackets, coupled with softer more malleable alloys allow the core to slip a little at engrave and take a set before exit.
The fellows who theorize that it is possible to shoot accurate HV with softer alloys, are also depending on using an alloy that is weak enough to take a set before exit.
Any of us shooting super hard alloys are getting the bullet nose twisted before the tail engraves (simple inertia here fellers) and the bullet has enough strength to try to straighten itself upon exit. This external "dishrag twist" is what causes accuracy to fail in my opinion, because it gives the centrifugal force something to get ahold of.
Using a slower twist barrel reduces this effect greatly, both at the engraving event, and with external centrifugal force. This is a double whammy that allows hard bullets to be shot at HV which is all to the good because they are more consistently effected by the barrel and are therefore more accurate.
Thats my opinion. Hate it if you want.

[vzerone]

Just a thought.
Everyone assumes the bullet gets "damaged" by the rifling and tries to make the science match that assumption. I do not believe this to be true. I have seen no evidence of it at all. The only damage I have seen was where the bullet stripped the rifling, but even that was done in a very consistent way around the bullet.
I do not believe the accuracy loss at HV is caused by bullet damage at all. I have a different, and very unpopular theory that squares with all the evidence of what was seen with the XCB project by those who contributed, by the paper patchers, and the fellows shooting sabots and copper jackets.


I think the bullet is releasing internal stress in flight because tough/hard alloys have enough strength to return to shape after being torqued.
The paper patch, sabot, and copper jackets, coupled with softer more malleable alloys allow the core to slip a little at engrave and take a set before exit.
The fellows who theorize that it is possible to shoot accurate HV with softer alloys, are also depending on using an alloy that is weak enough to take a set before exit.
Any of us shooting super hard alloys are getting the bullet nose twisted before the tail engraves (simple inertia here fellers) and the bullet has enough strength to try to straighten itself upon exit. This external "dishrag twist" is what causes accuracy to fail in my opinion.
Using a slower twist barrel reduces this effect greatly, both at the engraving event, and with external centrifugal force. This is a double whammy that allows hard bullets to be shot at HV which is all to the good because they are more consistently effected by the barrel and are therefore more accurate.
Thats my opinion. Hate it if you want.

I won't throw out your opinion. I'll ask then what can one do if he wants to shoot high velocity in a fast to overcome what you just explained? How do you load for it? It has to be beat somehow.

[MBTcustom]

I won't throw out your opinion. I'll ask then what can one do if he wants to shoot high velocity in a fast to overcome what you just explained? How do you load for it? It has to be beat somehow.

It can be beat as long as you keep the range less than 100 yards.
Other than that, the only way I have seen demonstrated with any degree of science is paper patch, Sabot, or Copper jacket.

Can't roller skate in a buffalo herd, and you can't get to heaven in a Cadillac.

[Cap'n Morgan]

Look at any recovered boolit, skidding occurs at the front band, usually none at the back.

It could be that the rear band skidding is counteracted by the bottom of the boolit being swaged while skidding, keeping the grooves "filled". The front part of the boolit, on the other hand, being under less pressure/force (per Longbow's explanation) will show some degree of skidding.

I'm just thinking aloud here, but it could also explain why a gas check is a good thing: It acts as a piston ring and will follow the rifling no matter how abruptly or fast the boolit is spun, due to its light weight. And it will still provide good sealing even if the boolit itself is skidding badly. (Sorry 44man, but I don't buy your "gripping" story ;-))

[vzerone]

It can be beat as long as you keep the range less than 100 yards.
Other than that, the only way I have seen demonstrated with any degree of science is paper patch, Sabot, or Copper jacket.

Can't roller skate in a buffalo herd, and you can't get to heaven in a Cadillac.

Please explain the 100 yards only.

I guess Elvis is poop out of luck then huh? LOL

[vzerone]

It could be that the rear band skidding is counteracted by the bottom of the boolit being swaged while skidding, keeping the grooves "filled". The front part of the boolit, on the other hand, being under less pressure/force (per Longbow's explanation) will show some degree of skidding.

I'm just thinking aloud here, but it could also explain why a gas check is a good thing: It acts as a piston ring and will follow the rifling no matter how abruptly or fast the boolit is spun, due to its light weight. And it will still provide good sealing even if the boolit itself is skidding badly. (Sorry 44man, but I don't buy your "gripping" story ;-))

Yes gas checks are a very good thing for cast bullets .

I have to ask, do you like Rum?

[44man]

Base integrity has to be maintained. I have recovered boolits with the entire check fully leaded so bad the copper can't be seen. Indications are they ran over lead. Not from my guns and I do not know the alloy as they were store bought.
What happens in the confines of the bore? Does it hold things together until free of the barrel where there are no more confines to the CF? We all have heard of a bullet turning to a puff of smoke out in front.
Also of importance is to maintain boolit shape and form with no slump.
You can get into a thousand things from powder choice and even boolit weight with more inertia.

[MBTcustom]

OK, the real (and good) subject. Goodsteel has evidence that a 'perfect' GC improves accuracy. This verifies that GC is to make a 'perfect' base. Yes, reduces gas cutting, scrapes leading, etc - as a side effect. Ths XCB mould/chamber design is to reduce distortion of the boolit when fired. Gain twist and different rifling patterns are not available for off-the-shelf guns. In reality it leaves alloy, pressure curve, lube/coating and boolit quality for us normal casters. In my few years of casting and shooting I've found you can get to 2700 (170gr. Cu GC 24" 308W 1:10 - and I tried an alloy that was close to superhard BHN wise) using 4% Sb H.T., 1800+ (300BO 18" 1:10 145gr PB) 3% Sb H.T.. 1 1/2 MOA @ 100 - mostly due to my lousy shooting - from an autoloader. You can figure the RPM. Would an XCB chamber and slower twist help? Probably but that costs $$. There are other threads here that try to answer a lot of the HV questions. I'm playing there just from curiosity.
I can't agree to that entirely, minimal effect compared to setting up the SS shock wave.

There are many things that are secondary as far as pressure goes, but what we are looking for is something that changes suddenly, well above the point where you get SS shock wave. Otherwise you couldn't shoot faster than 1200 FPS without losing your accuracy. Accuracy typically bites it at 140,000 ish RPM (give or take). That is typically above 1800fps which is way past where SS shock wave happens.
Also, I was shooting my 35XCB rifle, and I was holding 2 MOA as long as I stayed below 2595fps. As soon as any load crossed 2595fps, accuracy began to open exponentially from there. That's not pointing to SS shock wave. It's pointing to a dynamic effect that gets worse much faster than it should, and happens to a bullet that was just fine 15fps ago.
Now, I'm not saying that released bullet tension is all there is to the story, but I do believe it's the biggest obstacle to shooting less than 3000 FPS with cast bullets. (Past 3000fps, something else, something much worse, happens.)
This releasing tension was the whole premise of my 30XCB bullet design, and the forum is lousy with pictures of groups shot with my rifles, sporting slow twist barrels, chambered for the 30XCB cartridge, shooting the 30XCB bullet at 3000fps give or take 100. Maybe I just got lucky? LOL!

Vzerone:
I can explain in three short words:
NON
LINEAR
EXPANSION

IE, if you back the target up to 25 yards, you can shoot 3500FPS with a 10 twist barrel and shoot nice little groups. The further you move the target away, the slower you have to shoot till you find yourself right in the middle of the RPMTH.
The purpose of the XCB Project as far as I was concerned was to get a HV solution that was good for tagging targets at longer ranges, otherwise HV is useless. Long range hunting is the only reasonable explanation for doing it in the first place. Therefore, if you cannot shoot a clay pigeon at 300 yards, it really doesn't matter how fast the bullets blow through the 100 yard target. See what I mean?

[popper]

This external "dishrag twist" is what causes accuracy to fail in my opinion Nope, stress/strain curves for our alloys are near vertical until deformation then near horizontal. Elasticity constant for our alloys are ~10, Cu is ~ 20, steel ~ 120. Hysteresis curve at low force values is near straight line, very wide afterwards - meaning deformation, for us, once deformed, force is required to put it back - spring-back is in the 0.002% range (0.00006" for 30 cal) - at best! Realistically, size pure and it is dimension of sizer. Add 2% Sn and it stays the same. Add 2-3% Sb and it grows 0.002% -and stays there. A 0.002% symmetrical size growth or equal torsional change is of no consequence. I don't disagree that crappy accuracy can be due to small fps variation, but the reason is not what you surmise. For $25 you can get the article 'elasticity hysterisis curve for lead from IOS'.
NON LINEAR EXPANSION don't think that is the term you really wanted to use.

[MBTcustom]

Simple Definition of expansion:
: the act of becoming bigger or of making something bigger : the act of expanding

No, I think that is exactly the term I meant to use. See the Webster definition above.

[vzerone]

There are many things that are secondary as far as pressure goes, but what we are looking for is something that changes suddenly, well above the point where you get SS shock wave. Otherwise you couldn't shoot faster than 1200 FPS without losing your accuracy. Accuracy typically bites it at 140,000 ish RPM (give or take). That is typically above 1800fps which is way past where SS shock wave happens.
Also, I was shooting my 35XCB rifle, and I was holding 2 MOA as long as I stayed below 2595fps. As soon as any load crossed 2595fps, accuracy began to open exponentially from there. That's not pointing to SS shock wave. It's pointing to a dynamic effect that gets worse much faster than it should, and happens to a bullet that was just fine 15fps ago.
Now, I'm not saying that released bullet tension is all there is to the story, but I do believe it's the biggest obstacle to shooting less than 3000 FPS with cast bullets. (Past 3000fps, something else, something much worse, happens.)
This releasing tension was the whole premise of my 30XCB bullet design, and the forum is lousy with pictures of groups shot with my rifles, sporting slow twist barrels, chambered for the 30XCB cartridge, shooting the 30XCB bullet at 3000fps give or take 100. Maybe I just got lucky? LOL!

Vzerone:
I can explain in three short words:
NON
LINEAR
EXPANSION

IE, if you back the target up to 25 yards, you can shoot 3500FPS with a 10 twist barrel and shoot nice little groups. The further you move the target away, the slower you have to shoot till you find yourself right in the middle of the RPMTH.
The purpose of the XCB Project as far as I was concerned was to get a HV solution that was good for tagging targets at longer ranges, otherwise HV is useless. Long range hunting is the only reasonable explanation for doing it in the first place. Therefore, if you cannot shoot a clay pigeon at 300 yards, it really doesn't matter how fast the bullets blow through the 100 yard target. See what I mean?

Goodsteel...it's Tim right? Okay to just use your first name? Some of that I can't go along with. I just didn't stumble upon this forum and sign up. I've been following it for quite some time. Just when I decided to sign up some big argument got out of hand and threads where closed. Some of the threads I wanted to be part of. So I know the past stories and methods for shooting (guess you all call it HV) so I'll use that too from now on. Two methods I saw were of course your 30 XCB method and the other method using a different alloy (softer then what the XCB program was using) and a fast twist. Oops I forgot that later method often used buffer and some ultra slow powders.

Why would you see non linear expansion, but not see that on j-words or paper patched? I've seen many fast twist rifles shoot exceptional groups with j-words and paper patched. I'll tell you a few things I don't think you will believe, or at least have a hard time swallowing. The rpm of a bullet to be high enough to deteriorate accuracy is beyond the material strength of the bullet. I've been involved in shooting cast from fast twist with normal alloys including Linotype. I read all the threads (and arguments) on shooting the 6.5 Swede. Other calibers too with a fast twist like the 223 in the AR's. I believe Runfiverun enjoys shooting cast from a variety of AR's he has in 223 and I've read where he mentioned one is a 7 twist and some very nice groups were shot from it at pretty decent velocities. Okay...the second thing you're not going to swallow easy is a friend and I were playing with the 6.5 cruise missile, yes from a Swede. We started pushing it up and up. It was shooting very nice until we got around 2500 to 2300 fps second. We wanted to do a test and push it past 2300 fps and we did at 2364 fps. It cut 3/4 inch slots in the target paper....all the bullets not just one. Looking at the bore it was a cast shooter's dream. Very clean no alloy fouling. In fact it has an even coat of powder carbon fouling around the whole circumference of the bore. Now here's the hard part to grasp hold of. We shot 2.5 or slightly larger groups at 100 yards with the bullet that was unstabilized. We have no explanation for that do you? We were laughing as we actually shot better groups with bullets keyholing then many shoot when the bullet is flying at a lower velocity and fully stabilized. We said "Well that load isn't going to work". Something about bumping up that velocity was drastically changing something with the bullet. Where they were shooting decent at 2250 fps at 207,692 rpm to 2300 fps and 212,307 rpm were starting to go bad You're only looking at a 4615 rpm difference. I don't know, maybe that 4615 isn't just an "only". Those rpm's are in the area where things shouldn't be working for HV with fast twist rifles with standard alloys.

There's something else going on and I'm going to do some test to feel that something out. Sorry about this being so long winded.
BTW this is why I asked about the surplus powders in another thread. I'm using regular canister powders you can buy off the shelf so far.

[MBTcustom]

Vincent, please, call me Tim. That is my name.

I know you've been around the block, and the last thing I want to do is cause a fight here. I have a strong opinion formed on logic and science (at least, it's the best I can do with what I have).
I apologize if I came across that way.


Why would you see non linear expansion, but not see that on j-words or paper patched? I've seen many fast twist rifles shoot exceptional groups with j-words and paper patched

That's the real beauty of my explanation! It totally squares with pp and jacketed that you mention. Read my replies carefully.


'll tell you a few things I don't think you will believe, or at least have a hard time swallowing. The rpm of a bullet to be high enough to deteriorate accuracy is beyond the material strength of the bullet.

Ha! I agree completely!!! I validated that with some help a long time ago.


Okay...the second thing you're not going to swallow easy is a friend and I were playing with the 6.5 cruise missile, yes from a Swede. We started pushing it up and up. It was shooting very nice until we got around 2500 to 2300 fps second. We wanted to do a test and push it past 2300 fps and we did at 2364 fps. It cut 3/4 inch slots in the target paper....all the bullets not just one. Looking at the bore it was a cast shooter's dream. Very clean no alloy fouling. In fact it has an even coat of powder carbon fouling around the whole circumference of the bore. Now here's the hard part to grasp hold of. We shot 2.5 or slightly larger groups at 100 yards with the bullet that was unstabilized. We have no explanation for that do you? We were laughing as we actually shot better groups with bullets keyholing then many shoot when the bullet is flying at a lower velocity and fully stabilized. We said "Well that load isn't going to work". Something about bumping up that velocity was drastically changing something with the bullet. Where they were shooting decent at 2250 fps at 207,692 rpm to 2300 fps and 212,307 rpm were starting to go bad You're only looking at a 4615 rpm difference. I don't know, maybe that 4615 isn't just an "only". Those rpm's are in the area where things shouldn't be working for HV with fast twist rifles with standard alloys.

Read what I wrote Vincent. Read it really really carefully. I believe you.


There's something else going on and I'm going to do some test to feel that something out. Sorry about this being so long winded.
BTW this is why I asked about the surplus powders in another thread. I'm using regular canister powders you can buy off the shelf so far.

In my opinion, that "something else" is that you are pushing the alloy hard enough to make it take a set in the barrel and exit with less movement than was otherwise possible.
I totally agree this is possible. I don't doubt it for a second. The big question is, IS IT USEFUL at long range, Is it REPEATABLE session to session? These are the questions that must be answered and have never been satisfactorily demonstrated on this forum.
The only way to tack down exactly what is happening is to make it happen repeatably in the first place, then start changing one thing at a time and note the difference, and throw out any theory that doesn't match the science, till you shake out the truth in all it's radiant glory.

That's all I'm saying.

[MBTcustom]

I think it has been previously referred to as non-linear dispersion (L.G.?). Here is an example. https://www.youtube.com/watch?v=hVKz9G3YXiw Look at the counterweight portion.
I don't know all the answers but digest this. Gasses in barrel tube create a pressure wave that is super/sub sonic at different portions of the tube. Upon exit,the tube shock wave and projectile shockwave interact. Surface rotational speed is 200ft/sec,(2333 rps) slow so only small turbulence is created (litle twist to the shock wave).The final shock wave angle is arcsin=1126/fps and changes rapidly at the crown. Any shockwave non-uniformity can cause movement of center of pressure against barrel face will have an effect on boolit, The pressure wave force is large. At 2600 fps vs 2650, theta changes from 25.144 to 24.645 deg, about 1/2 deg.If the barrel surface is slightly off kilter, the shock wave will tilt the boolit. For a 1"dia. barrel this means the shock wave (boundry edge) clears the muzzle about 1.5" from the apex of the wave (boolit nose).
An overspun gyro (unbalanced at that rotational velocity) will jump when uncaged, like the off balance boolit leaving the constraints of the barrel. RPMTH.
Either will cause the neutating path to the target.
I shoot flat nosed boolits, when the nose gets dinged, accuracy is off. I have to assume it's due to both the above effects.
Interesting read: https://books.google.com/books?id=PmuqCHDC3pwC&pg=PR12&lpg=PR12&dq=creation+of+supersonic+shock+wave&source=bl&ots=ocKzbfWoWm&sig=JjyN5Y6s6kA9ZkaoCCKa3PmUq0k&hl=en&sa=X&ved=0ahUKEwjLnOW81ZPKAhUB3CYKHX1oB-g4ChDoAQhEMAc#v=onepage&q=creation%20of%20supersonic%20shock%20wave&f=true

OK, so if that's true, then how am I able to so easily change the outcome by modifying twist rate?
if shockwave was the only thing going on here, then my modifying the twist rate of the gun would have no effect whatsoever.
Why would that not effect jacketed in the same way?
Why would that not effect paper patch in the same way?

[runfiverun]

paper loses it's jacket at the muzzle and that extra blast helps it do so.
it won't even shoot well until you get it to jacketed speeds.
you need the lands to cut the paper and if you do not get confetti at the muzzle you get nothing on target.
paper relies on pressure/velocity to work properly.

[Walkingwolf]

Man goes to an upscale doctor with a swollen bleeding thumb, the doctor runs thousands of dollars in tests, schedules surgery to repair the thumb. Still paying for the surgery, and expensive doctor the man goes to a country doctor with a swollen bleeding thumb. Doctor looks at thumb, and says "Dayum, this looks like you have been hitting it with a hammer". Patient says "Why yes I have". Doctor says "Don't do that".

I will let you guys argue over the moral of the story.

[vzerone]

Tim - expansion to me means what a tire does when spun fast - dia. grows in the middle of the tire. That idea would tend to be invalidated by PP with soft, fast and accurate & PP falls away at the muzzle. But that expansion would/should be symmetrical. That brings up the idea that the alloy has to be strong enough to withstand centrifugal forces at 200K RPM (2700 1:10). The RPMTH of 144K moves with twist, but why the 144K number? It is alluded to be related to material strength, but it seems noone wants to factually state that. It seems to be related to your house alloy & Larry's alloys. My thought is damage when fired and exit are the critical area, the ride down the bore is pretty uneventful. My shock wave stuff is supported by those who use a hacksaw to shorten the barrel, even if crowned properly. Interesting that most target rifles have a flat faced end vs the rounded of hunting rifles. Vzerone started this threat in interest of HV accuracy, I'd like to offer you some cast of PCd, H.T.d high Cu content to do your GC trick & get tests in 30XCB rifle for comparison. My shooting skills and range just won't allow a proper test. Your hammer-of-thor results on deer may have been more hydrostatic shock (3k fps) than hard alloy - why I really wanted to get that pig with the lower fps BO. IMHO that is the reason you are sticking with your alloy. Not trying to argue, just separate fact and fiction.

I'm leaning more along the lines of something happening to the bullet at the exit of the barrel. I'm trying to devise some test to see what I can find out.

[geargnasher]

Spark gap photography is affordable and may be of assistance in that.

Gear

[popper]

vzerone - AF spent big bucks trying to get actual photos (T33 & cessna chase plane), not vapor photos we see. Most of the testing and photos are done in wind tunnels and shock tubes using high speed diffraction photography. The phenomena is the same in water (speed of sound/motion is much lower) and much easier to film and understand the interactions of the wavelets. A lot is in scientific journals but you have to wade through a lot to find it. Much is found in tsunami experiments.

[vzerone]

Geargnash & Popper,

Well I didn't mean to test it like that exactly. I have some shooting test with loads I'm going to modify and see what affect the modification have on overall performance and accuracy.

I'll tell you though it sure would be nice to have that high speed camera.

[geargnasher]

Process of elimination: Linotype is no good at HV, though less bad in slower than normal twists. Slow twist only mitigates the HV degradation slightly, enabling 2 MOA at best at near jacketed velocities vs. the sub-MOA capable of better alloy in standard twists. Alloy suitable for swaging works better at HV.....too much tin and it's no good. Gas checks a must unless using a jacket of some description. Buffer helps even if just used where it acts as a cushion and not necessarily a burn-rate modifier. And of course, the doozy...the paper jacket.

We know bullets can be easily hand-cast (even from a bottom pour with some skill) to withstand high rpm....again because of the work done with paper jackets. So it isn't always casting quality that challenges accuracy at HV. Breech seating improves plain-based bullet accuracy more noticeably than it does gas checked bullets.

So let's put all that data together for a minute and ignore the relatively marginal accuracy-improving techniques of exact case fit in the chamber, small neck clearance, throat-matching taper, precision-sleeve seating dies, uniform neck tension, etc. What's left? Note the paper jacket offers the single most viable accuracy/velocity improvements that are easily obtainable for our cast bullets. Question is WHY?

ANSWER: Helps the bullet start straight, stay straight, obturate the bore, hold the rifling, and exit the crown straight.

I'll venture to say with regard to normal, lubed, gas-checked cast bullets, that the straight start can be made by proper case prep and bullet fit, bullet alloy selection, and powder burn speed...but that's not the whole deal. Bullets tend to stay straight once started straight....unless gas cutting occurs or other issues during acceleration such as excess abrasion. Obturation is the same, a good lube that doesn't fall on it's face at HV helps, and alloy choice and temper makes or breaks it...and it's STILL a limiting factor. Exiting the crown straight is made possible by not buggaring the gas check at launch, or the shank collapsing due to a casting void, or a crooked start of the bullet into the throat that swages the base in there at what becomes a permanent skew. Buffer also helps keep gas off the bullet base at crown exit when the uncorking occurs. What's the most important thing a paper jacket does to improve HV accuracy? I don't know for sure, but I've spent a lot of time perfecting every aspect of the HV loading process that I know to address, and the ultimate limiting factor is the engagement of the bullet into the lands at high velocity. Add a paper jacket and that goes away completely, allowing easy sub-MOA groups out to the transonic point and full-on copper-jacketed bullet velocities and often above with modest pressures if done correctly.

Oh, I left out barrel harmonics, but that is easily mastered through consistent ignition, bore condition, and loading to a node.

So the whole dealy-o with getting great accuracy with regular bullets at HV is getting the pressure and alloy to work together just exactly right so things don't fall apart in the barrel...and either a crooked start or damaged engraves occurs, or both. Process of elimination.

A nice series of photos of bullets in flight about 3' in front of the muzzle representing the gamut from "normal" velocities to the area where it starts to lose accuracy, and beyond, would explain a lot. If it's ever done, I postulate that the land engraves on the bullets that begin going off into the twilight zone are going to show some evidence of gas-cutting and leading edge abrasion.

Gear

[vzerone]

The thing that is bad about loading to the node in barrel harmonics is that you are limited to what that load has to be and you can't readily change it much, thus where it works may be where you don't want to be, or said another way it doesn't get you to where you want to be.

[vzerone]

Geargnasher you left out something in your last post. I will throw you another curve. What you left out are the Barnes Henninger bullets and Wilkes checks. These as we know are copper (or copper alloy) driving Webands cast into the bearing bands of a cast bullet. These raise the velocity of cast bullets to the j-word level, albeit it without startling accuracy. So that brings us back to something is going on in the bullets travel down the bore. We are back to the beginning of the three crucial areas of cast bullet shooting which are starting the bullet straight (this includes anything having to do with the base), the trip down the bore through the rifling, and the exit from the muzzle. If you read the NRA Cast Bullet Book thoroughly testing was done to try ease the bullets exit from the muzzle. They tried such things as powdered Teflon (which was the best) to other fillers such as sawdust, Cream Of Wheat, Kapok, grease wads, and more likely a whole host of others. Although some worked the accuracy consistency wasn't where they wanted it to be. Mann knew and talked of this too. It appears that the PP bullet covers all three of these areas quite well and the question, again, is why?

[runfiverun]

maybe looking at the cure is the answer or the partial cure I guess I should say.

think about what all of those have in common.
they are all protecting the base of the boolit.
I remember Bass tellin me about protecting the base of the boolit from the mold to the target was they key to getting it there at higher speeds.

one of the things he was working on was pushing a boolit to 2700 fps with under an inch accuracy.
he could only do it consistently with 3 to 4 shots then had to cool everything down and wait to do it again.
now I correlated this is with some P/P success I have with the oldest girls 7.7 rifle.
I don't see the confetti at the muzzle [heck I don't find any paper anywhere] but the accuracy is stellar for the first 3 shots and then poof it's gone.
and by gone I mean no accuracy whatsoever.
now I'm not loading these like your typical paper patch smokeless powder type load.
I'm loading them more like a paper wrapped cast boolit with .002 neck tension on the case, and a severely undersized nose. [like .298 in a 304 bore]

I wondered if the balance is so critical at that point that just the heat generated from shooting the gun is enough to throw some of the fitment off somewhere changing things that shrink back into place when at ambient temperature allowing the system to work again.
or is the heat slightly altering the lube making it a little bit more wet before starting things on their journey.

[BAGTIC]

Recoil is based on momentum not kinetic energy.

[vzerone]

maybe looking at the cure is the answer or the partial cure I guess I should say.

think about what all of those have in common.
they are all protecting the base of the boolit.
I remember Bass tellin me about protecting the base of the boolit from the mold to the target was they key to getting it there at higher speeds.

one of the things he was working on was pushing a boolit to 2700 fps with under an inch accuracy.
he could only do it consistently with 3 to 4 shots then had to cool everything down and wait to do it again.
now I correlated this is with some P/P success I have with the oldest girls 7.7 rifle.
I don't see the confetti at the muzzle [heck I don't find any paper anywhere] but the accuracy is stellar for the first 3 shots and then poof it's gone.
and by gone I mean no accuracy whatsoever.
now I'm not loading these like your typical paper patch smokeless powder type load.
I'm loading them more like a paper wrapped cast boolit with .002 neck tension on the case, and a severely undersized nose. [like .298 in a 304 bore]

I wondered if the balance is so critical at that point that just the heat generated from shooting the gun is enough to throw some of the fitment off somewhere changing things that shrink back into place when at ambient temperature allowing the system to work again.
or is the heat slightly altering the lube making it a little bit more wet before starting things on their journey.

The Wilkes check aren't protecting the base of the bullet which should already have a gas check, but we know that's not enough. So we are back to square one. PP bullets shoot pretty good, Wilkes check bullets shoot pretty good. Regular gas checked bullets are very hard to make shoot good. That makes it appear that the sides of the bullet are the problem. Just thinking out loud hear. So what's different between the PP, Wilkes checks, and plain just gas checked? On the PP and Wilkes check the sides (or at least the bearing bands) are protected. Now we're talking high pressure and high velocity here...not the ordinary lower velocity cast loads. So is it possible that the sides of the bullet are getting damages in some manner that they then don't spin true because this damages upsets the balance of the bullet? Notice that this HV inaccuracy doesn't just start, it gradually starts and gets worse. So could we be lead to believe the faster you put the bullet the more damage is done to the sides of it?

Edited to add another thing that the PP and Wilkes checks have the regular gas check bullet doesn't have is more bearing band strength or in the case of the PP more bearing band area. Can't do more bearing band area with a standard cast bullet because you have to have area for lube. Loverins don't cut it because the bearing bands are too narrow.

[popper]

https://en.wikipedia.org/wiki/Shadowgraph#/media/File:Supersonic-bullet-shadowgram-Settles.tif
https://en.wikipedia.org/wiki/Schlieren_photography High speed bullet videos, second one is at the muzzle exit. Pretty complicated waves.
157522

[geargnasher]

Run: Undersized noses are a delicate thing with PP... I have often thought the same thing about barrel heat and have observed the same pattern of can't hit the berm after a few shots.

"Vincent": The question to ME is what do we have to do to regular bullets to get them to shoot like PP?? You speak truth about Loverins, no good for HV in normal twists in most cases (exceptions are barrels with xtra-wide lands, and a new one to you, 5R polygonal rifling). Loverins work good at LV because they engrave easily without getting damaged and can be a lot oversized and still work because there's lots of room for metal to move without distorting the core shape of the bullet. BUT...not much bearing surface.

The Wilkes check bullet may not be a fully valid comparison unless YOU or I shot some of them and positively eliminated faulty loading techniques. Done correctly, those puppies might shoot to the absolute velocity limit (pressure limit) of a cartridge with stellar accuracy if the launch isn't screwed up. I'm still not convinced that hard driving bands aren't the full answer to getting cast bullets up to full speed with accuracy, ASSUMING one knows how to get the other details right. What I'm saying is a straight launch and crown exit are within the control of the handloader, but engrave abrasion down the barrel might be the limiting factor caused by the material (lead alloy) that we're trying to use. I'm still looking for that miracle and finding it just might not happen. That's ok, I'm good with 2400 fps /moa in most rifles by matching bullet design, powder, and alloy to exactly what the rifle likes.

Also, you mentioned harmonics. If the rifle ain't happy where you're happy, get a barrel tuner. I think you're already ahead of the game on that one.

Gear

[vzerone]

https://en.wikipedia.org/wiki/Shadowgraph#/media/File:Supersonic-bullet-shadowgram-Settles.tif
https://en.wikipedia.org/wiki/Schlieren_photography High speed bullet videos, second one is at the muzzle exit. Prety complicated waves.

Yes, but that's a shotshell (more then likely a 12 ga) and that's a big area mass compared to a rifle bullet. Lots going on no doubt.

[popper]

First one is a rifle.
I shoot PC boolits, pretty fast too. IMHO, the paper filament FIBERS add strength (till shredded) and cushion the first blast but most contain some form of clay which, although not real abrasive, may change lube capabilities. PC doesn't have the fibrous strength.
157524
fps calculated from Larry G pressure trace 308 - 24" barrel chronyd ~2200 fps IIRC so Y axis is x10. Initial fps is very low! Pressure has to get to 5K psi or so before much movement takes place. By X=4, boolit is in bore.

[vzerone]

You made me thing of something crazy. What if you shot a HV cast load in a vacuum, say like outer space if we would have the same negative results? The atmosphere influence would totally eliminated.

[44man]

I could never wrap my head around why paper works and never tried it.
One thing I understand is a straight start and might be the cause of so many high velocity problems because it gets worse the faster you shoot.
Run out is common with cast but is hard to measure on a boolit because most are not round to start with and then the parting lines will drive you nuts.
Just with my 30-30 I was getting .022" run out on the end of the brass so imagine out on the boolit. Only thing I can measure is the end of the brass and my boolits are more round then most molds can make.
Anyway I found neck thickness was the cause so I turned to just clean up. Then I use Hornady dies with the great seater die. I went down to .000" to .002" at the end of the brass and can see no boolit wobble when rolled on my bench.
If a boolit has .009" run out, Would you think lead will straighten out? Might be why "J" words work better.
How many of you looking for extreme velocities have measured your boolit start?
Just roll a round on a nice table, if you see the nose wobble just a little, you are already done. Bad start, faster twist and higher velocity do not go together.
Fit the boolit tighter into the leade or engrave the boolit more might work but you are fighting the brass to respond and get straight. You could bend boolits that way. Breech seating eliminates the brass, wonder why they did that?

[vzerone]

I could never wrap my head around why paper works and never tried it.
One thing I understand is a straight start and might be the cause of so many high velocity problems because it gets worse the faster you shoot.
Run out is common with cast but is hard to measure on a boolit because most are not round to start with and then the parting lines will drive you nuts.
Just with my 30-30 I was getting .022" run out on the end of the brass so imagine out on the boolit. Only thing I can measure is the end of the brass and my boolits are more round then most molds can make.
Anyway I found neck thickness was the cause so I turned to just clean up. Then I use Hornady dies with the great seater die. I went down to .000" to .002" at the end of the brass and can see no boolit wobble when rolled on my bench.
If a boolit has .009" run out, Would you think lead will straighten out? Might be why "J" words work better.
How many of you looking for extreme velocities have measured your boolit start?
Just roll a round on a nice table, if you see the nose wobble just a little, you are already done. Bad start, faster twist and higher velocity do not go together.
Fit the boolit tighter into the leade or engrave the boolit more might work but you are fighting the brass to respond and get straight. You could bend boolits that way. Breech seating eliminates the brass, wonder why they did that?

Well we know that 44man and that's not to slight you one bit. Even if a j-word is started crooked they are less accurate.....and j-words sometimes do start crooked. I'll tell you a way to see that. You have to use j-word boattails. Try to recover one that's not damaged too bad especially the base. Okay if you examine it rotate with your finger and look on the rifling cuts protrudion, or should I say extrusion, over the taper of the boattail. You know how rifling extrudes a little bit of metal? On a boattail that wasn't started perfectly straight you will see one or more (depending on how many grooves your bore has) grooves that don't extend over as much as the others. That shows the bullet wasn't straight.

PP is great in one way and terrible in another. They are a bear to wrap, don't care what anyone says. I like to take a bullet and seat it. Don't want to wrap wet paper and let them dry and all. The other is IF YOU USE the wrong paper they are abrasive whereas the proper cast alloy is not as abrasive. The wrong paper is the stuff with clay in it.

I've spun my cartridge looking for run out. When I discovered I had round out on a 7x57 I switched seating die types and eliminated a good portion of my run out.

Seating bullets into the rifling is only a cure for lower velocity stuff. In other words it's a beginner trick to get a little more accuracy. An analogy would be a kid learning how to ride a bicycle. He's small and starts with a small bicycle. As he grows older and bigger he goes to larger frame/wheel size. Soon he's an adult and rides an adult bicycle. Okay loading the cartridge so the bullet engraves the rifling deep is middle size bicycle.

Neck thickness concentric is important for accuracy, but you must be a good shooter and have basically bench equipment to see the difference in my opinion.

[runfiverun]

one small thing I have noticed has worked every single time to gain more velocity is to use more bearing surface.
now I like a nose as much as anybody but for the sake of higher speeds you do not need very much of one to do the job.
some of the designs I know will shoot 2400 and above would be better suited with less nose weight and as much bearing length as possible.
in fact seating the base of the gas check slightly below the neck shoulder junction would make the most of this length if you extend a smooth sided drive band forward into the ball seat area.
this of course would slide the c.o.g. into a different place but so does a hollow point and they generally shoot better.
the question is how much goes and how much stays?
you have to have some there to help the transition from the bigger throat area down into the barrel.
we are talking about .001 worth of material being squished into place here if you can get a rifle with proper dimension.
.0010 neck clearance just ain't gonna cut it.

[geargnasher]

Case in point about bearing length, I sometimes get better results with the Mihec .30-sil when I kick it hard in the pants and don't use any buffer. Bearing surface increases forward of the lube groove the harder you hit it from behind. Loaded in a .308, it's the only time I've seen buffer make a load shoot worse.

Gear

[vzerone]

Geargnasher what you said about the 30 and kicking the harder well just about any bullet is going to do that providing the proper alloy and hit hard enough.

[runfiverun]

Case in point about bearing length, I sometimes get better results with the Mihec .30-sil when I kick it hard in the pants and don't use any buffer. Bearing surface increases forward of the lube groove the harder you hit it from behind. Loaded in a .308, it's the only time I've seen buffer make a load shoot worse.

Gear

now that's something to really think about...

what exactly happened to the boolit under those circumstances.
I know you have thought about it, but anybody else reading this should take a look at the design and guess what is happening and where.
I have a handful of those boolits here I pretty much know what happened.

I use a similar [but lighter weight 165grs] design and keep thinking of doing a slight re-design and dropping more weight [getting into the 145gr area] off the front would add more velocity instantly.
adding in more length to the drive band area to fit the 30-06 throat/neck with more full diameter drive band area.
I THINK that slight change in weight and such should be good for almost another 200 fps, and could possibly allow for a faster powder speed.

[vzerone]

Shooting cast using the Wilkes method equals j-words straight across. They are just a royal pain to make and expensive. I'm surprised you haven't tried them Geargnasher especially since you've done PP.

[44man]

Of course I agree any bullet must be straight too, the worst run out can be case shape too. Weatherby brass is the worst for bending a shoulder fast. I found the expander plug was pulling the rounded shoulders because my Redding dies sized too much to start with. I sent the size die and fired cases to Redding to get lapped for minimum sizing. Instant success with 1/2" or less at 100 with every load tested. Redding collar dies really work along with an inline seat die.
Still, cast run out is hard to measure so an M1 eyeball on the bench can tell a lot. If the nose wobbles, you must track down where it starts.
Most run out is in the brass before you seat and neck thickness that varies forces brass off center in the size die. Pulling the expander if tight adds another bend.
I firmly believe you gain in any gun by using BR techniques.
The Wilk's method does work too by starting to stop skid early and I made my own tool for punching the center out of GC's so I can cast the check anywhere. I did it for the .44 Keith style and at the front drive band it helps steer at the cone but is no better in the revolver then a proper ogive.
Gear and Runfiverun make good points too. Bearing surface is important. I still do not believe in slump to fit the rifling. I do not believe in more expansion on the trip down the bore to seal. All damage to a boolit is instant, before it even moves. The slower you start it before peak pressure, the better. Then build pressure when the boolit is moving.

[btroj]

Nothing in life is instant. Even a nuclear explosion takes time. The bullet takes time to slump or otherwise change shape and that time and the pressure required mean the bullet must move while it is happening. Think in small terms, milliseconds and fractions of an inch. But move it does.

I got decent, not great, but scent accuracy using a low Sb, low Sn alloy heat treated with a faster than expected powder. The bullets did not engrave the nose when inserted in the muzzle but shows rifling marks when recovered. Those bullets certainly did fatten in the nose on firing. Bullet was the MP 30 sil. A great bullet design for most 30 cal rifles.

I agree with Gear and Run, slow start, right alloy, right peak pressure. We really aren't going to prevent all shape change in the bore so why not use it to our advantage. Rather than fighting the change, try to make it happen in a way we can control.

[44man]

I agree with Gear and Run, slow start, right alloy, right peak pressure. We really aren't going to prevent all shape change in the bore so why not use it to our advantage. Rather than fighting the change, try to make it happen in a way we can control. Quote'
Same page are we? Control and testing is where it comes together. Yet boolit inertia when kicked in the butt can't be ignored even if milliseconds. I suppose a boolit can move a few millionths of an inch before deforming but why deform it at all? Does expanding a boolit nose into the rifling at peak make it accurate? Veral says a long bore ride in a micro groove is wrong with more drive bands better.

[vzerone]

44man,

I don't use the standard sizing dies and that have the expander, which is set for j-word expansion, to load my cast. I believe in minimum case work. By work I mean any operation that hardens the brass. I use bushing dies and they are set so the necks are just about right at the right inside diameter for proper neck tension. Yes of course the necks have to be turned for that.

If you have a case with varying neck thickness and you size it in a sizer die that is perfectly true, it squeezes the neck unevenness to the inside of the neck. If you don't drag an expander ball through it, it should be a true case if you spin it. I'll tell you that the insides of the necks should be clean.

It probably doesn't matter too much on revolver bullets using Wilkes checks, but on rifles especially shooting HV that the hole in the Wilkes check is perfectly centered. If it's not there's going to be a noticeable imbalance.

Talking to competition shooters in the accuracy games the two most important case preps are internal case volume and neck thickness. And you really aren't going to see the difference with BR techniques in a run of the mill rifle such as an old milsurp. Also in talking to the competition boys primer flash hole size is more important then deburring the flash hole.

Their is no set rule that you absolutely have to start a bullet slow. It has taken many people on this forum a long time to realize that cast bullets bump up, obturate, expand, which ever you wish to call it (except I hate the word slump or nose slump) when the gas pressure hits it and if that pressure is enough, also the alloy is proper for this to happen. Even j-word bullets do this, but on many it's barely noticeable. Here are some dictionary definitions of slump:
sit, lean, or fall heavily and limply, especially with a bent back.
"she slumped against the cushions"


synonyms:
sit heavily, flop (https://www.google.com/search?biw=1408&bih=664&q=define+flop&sa=X&ved=0ahUKEwjU2ofozZrKAhUB7CYKHbW2A2oQ_SoIHTAA), flump (https://www.google.com/search?biw=1408&bih=664&q=define+flump&sa=X&ved=0ahUKEwjU2ofozZrKAhUB7CYKHbW2A2oQ_SoIHjAA), collapse (https://www.google.com/search?biw=1408&bih=664&q=define+collapse&sa=X&ved=0ahUKEwjU2ofozZrKAhUB7CYKHbW2A2oQ_SoIHzAA), sink (https://www.google.com/search?biw=1408&bih=664&q=define+sink&sa=X&ved=0ahUKEwjU2ofozZrKAhUB7CYKHbW2A2oQ_SoIIDAA), fall (https://www.google.com/search?biw=1408&bih=664&q=define+fall&sa=X&ved=0ahUKEwjU2ofozZrKAhUB7CYKHbW2A2oQ_SoIITAA); informalplunk oneself
"he slumped into a chair"







[LIST]
1a : to fall or sink suddenlyb : to drop or slide down suddenly : collapse (http://www.merriam-webster.com/dictionary/collapse)

2 : to assume a drooping posture or carriage : slouch (http://www.merriam-webster.com/dictionary/slouch)

3 : to go into a slump <sales [I]slumped>

Those aren't happening to the cast bullet. It's a bad terminology for what is occurring.

[runfiverun]

a long bore ride is always wrong at higher velocity's.
if you want proof of that read the rpm theory threads.
[really read them and dissect what really happened there, don't just take them at face value as fact]
there is no way a long parallel sided boolit is going to take that velocity or twisting motion, the faster twist rate just proved out that ruining an ill fitting mold even more upon firing with a too fast powder is gonna show up sooner when spun faster.

I would like to see the rpm thread re-shot with an actual boolit mold designed around re-throated and chambered rifles giving everything an actual chance.
the XCB design was an attempt at getting this right but even there sloppy neck clearance was allowed and that is one of the biggest hurdles we face when getting this done.
I want to run a 309 boolit in .0011 thick brass with .002 total outer neck clearance,,, just once,, that isn't too much to ask.
then I know 100% for sure that what I am fighting is alloy, boolit design, and barrel interface.
not boolit destruction in the throat, uneven slumping, flummoxed head scratching or crooked anything.

[btroj]

Ok, slump isn't the right term. Call it what you will but the bullet WILL change shape at least a little under pressure. The alloys we use all act in a plastic manner under pressure.

What word is best used to describe the change in shape of a bullet under pressure?


I don't believe it is possible, using realistic alloys, to cast bullets that resist all deformation. Even Linotype will respond to pressure by altering shape some.

[vzerone]

Ok, slump isn't the right term. Call it what you will but the bullet WILL change shape at least a little under pressure. The alloys we use all act in a plastic manner under pressure.

What word is best used to describe the change in shape of a bullet under pressure?


I don't believe it is possible, using realistic alloys, to cast bullets that resist all deformation. Even Linotype will respond to pressure by altering shape some.

Well if you've been following along I like to call it bump up, obturate, expand, even swage. Out of those I like expand the least.

[vzerone]

a long bore ride is always wrong at higher velocity's.
if you want proof of that read the rpm theory threads.
[really read them and dissect what really happened there, don't just take them at face value as fact]
there is no way a long parallel sided boolit is going to take that velocity or twisting motion, the faster twist rate just proved out that ruining an ill fitting mold even more upon firing with a too fast powder is gonna show up sooner when spun faster.

I would like to see the rpm thread re-shot with an actual boolit mold designed around re-throated and chambered rifles giving everything an actual chance.
the XCB design was an attempt at getting this right but even there sloppy neck clearance was allowed and that is one of the biggest hurdles we face when getting this done.
I want to run a 309 boolit in .0011 thick brass with .002 total outer neck clearance,,, just once,, that isn't too much to ask.
then I know 100% for sure that what I am fighting is alloy, boolit design, and barrel interface.
not boolit destruction in the throat, uneven slumping, flummoxed head scratching or crooked anything.


Runfiverun you are so very correct about that bore rider. I did a test once to see how fast I could push a bore rider. I was able to get it key holing at a distance of 10 feet.

Lyman Loverins are another one not to push to high velocity mainly because of the very narrow bearing bands. Geargnasher said you can in a barrel that has wide grooves. That's not exactly true either as I have such a barrel and it's no dice with it and the Lyman Loverin. Oh you may get a little more out of it with wide grooves, but not much.

One more thing Run, you can get very good accuracy from a bore rider in a very fast twist..NOT AT VERY HIGH VELOCITY THOUGH!!!

[btroj]

I like swage. Our bullet responds to pressure by filling available space just like a swage die works. Alloy composition and pressure control the amount of seating that occurs.

[vzerone]

I like swage. Our bullet responds to pressure by filling available space just like a swage die works. Alloy composition and pressure control the amount of seating that occurs.

Well the only thing I don't like about using swage is that it reminds me of swaging dies. They have dead ends at both ends whereas in a barrel the bore ahead of the bullet is always open.

BTW you are very correct that the bullet or the bullets nose changes shape.

[geargnasher]

I call it "bump" because the force that causes the plastic deformation is powder pressure from behind causing the bullet metal so "pressurize" and expand from the rear forward within the confines of neck/throat/bore, not the static inertia of the unsupported parts of the nose flowing backwards under launch acceleration.

Run, I've achieved that level of neck clearance using blank brass in a .308, and while it helps, it isn't the whole answer at HV. That's how I was getting MOA accuracy out of a bone-stock Savage 20" hog rifle at ~2300 fps...together with heat-treated low-antimony alloy, a self-aligning bullet, and just the right amount of the right kind of powder. Necks were cut down to around .022" thick IIRC to make up the enormous factory chamber neck clearance to under .001" total with .310" bullets. Some say they can do that level of velocity and better accuracy with the exact same bullet and alloy without using thick-necked brass, but I haven't figured out the trick yet. I know bigger bullets (like .312-.313") were used, but the same person who told me that also told me he doesn't use bullets that are bigger than throat entrance diameter, either, so take that FWIW. When I tried swage-able alloy at near jacketed pressures and had a bullet that was any at all larger than throat diameter, I got lead rings and a whole lot of heavy grey wash in the throat, end of chamber, and on down the bore.

Gear

[35 shooter]

Runfiverun you are so very correct about that bore rider. I did a test once to see how fast I could push a bore rider. I was able to get it key holing at a distance of 10 feet.

Lyman Loverins are another one not to push to high velocity mainly because of the very narrow bearing bands. Geargnasher said you can in a barrel that has wide grooves. That's not exactly true either as I have such a barrel and it's no dice with it and the Lyman Loverin. Oh you may get a little more out of it with wide grooves, but not much.

One more thing Run, you can get very good accuracy from a bore rider in a very fast twist..NOT AT VERY HIGH VELOCITY THOUGH!!!
vzerone

Just to understand this "bore rider" thing a bit better, just at what "high" speed is a bore rider supposed to fail to shoot accurately on average?

Say from a 1/14 twist in 35? Would it be at around 2000, 2200, more?

[geargnasher]

Nothing in life is instant. Even a nuclear explosion takes time. The bullet takes time to slump or otherwise change shape and that time and the pressure required mean the bullet must move while it is happening. Think in small terms, milliseconds and fractions of an inch. But move it does.

I got decent, not great, but scent accuracy using a low Sb, low Sn alloy heat treated with a faster than expected powder. The bullets did not engrave the nose when inserted in the muzzle but shows rifling marks when recovered. Those bullets certainly did fatten in the nose on firing. Bullet was the MP 30 sil. A great bullet design for most 30 cal rifles.

I agree with Gear and Run, slow start, right alloy, right peak pressure. We really aren't going to prevent all shape change in the bore so why not use it to our advantage. Rather than fighting the change, try to make it happen in a way we can control.

Just quoting this so everyone can read it again.. particularly the part about using the inevitable to our advantage rather than wasting a whole lot of time, money, and gunsmithing, and linotype trying so desperately to PREVENT it. Even jacketed bullets bump and swage!!! Solid copper and brass bullets not so much, so they have to have relief cuts similar to lube grooves to give the metal displaced by the lands somewhere to go. Remember that jacketed and monolithic bullets are typically made to groove dimensions, not the typical .002-4" larger than groove of our cast bullets, so there is even less metal to be moved yet the bullets still elongate (jacketed, measured by change in BC after firing) or displace metal into the grooves (monolithic).

Gear

[vzerone]

vzerone

Just to understand this "bore rider" thing a bit better, just at what "high" speed is a bore rider supposed to fail to shoot accurately on average?

Say from a 1/14 twist in 35? Would it be at around 2000, 2200, more?

35 I don't know the exact figure. The one caliber I was playing with was 7.62x54R. The bullet was a Lyman 314299. I believe the velocity it failed at were above 2500 fps.

On that 14 twist question it would be more. You may not achieve it as your shoulder will give out first. I would think too that larger caliber/diameter bullets may be more forgiving.

[vzerone]

Geargnasher about that getting accuracy without having to use thick necks....just think about it. Think about what the thicker necks are doing. Then think about what you have to do to get there without the thick necks.

I mentioned that most or all j-word bullets bump up some too. It may not be noticeable on some as the measurements of bump up are very far to the right of the decimal point. Ones that don't are the ones you retrieve and the land on the bullet (that's what I call the part of the bullet that forms in the barrels groove, have black powder carbon streaks on all of them tells you that bullet didn't fill the grooves in the barrel the full depth. I know the ones that do are discolored, but you can tell the difference in appearance between the two. You can see this in the barrel too. There will be bullet alloy deposits on top the lands and in the grooves, but where the bullet doesn't fill the groove entirely the bottom center of the groove won't show that deposit.

You know know that those grooves on Barnes copper bullet are to reduce friction and alloy fouling, not specifically so displaced bullet metal has a place to go right?

[35 shooter]

OK, thanks vzerone. Lol i consider 2500 to be fairly high velocity with cast. I guess i should have specified something like 1.5" or better @ 100 yds. with 5 or 10 shot groups.

I've got up to 2400 with a 280 gr. bore rider in my whelen, but groups are 2" or a bit more depending on powder used so far. Holes in the target still straight...no yawing.

Thanks and i'll keep playing with powders and seating depth a bit more.

BTW recoil is no problem even with one hand on the rifle from the bench as far as my shoulder. Lol the i noticed the problem is the scope "hunting" my eyebrow at over 2400 fps.....may have to use two hands from this point on!!

[vzerone]

35 shooter that is very good with your 280 in my opinion. There are so many things you can try that it's mind boggling. Keep up the work you have done so far.

[popper]

157573
For what it is worth, chronyd @ 2112 fps. Plain base 145gr. 300BO loaded to ~40K CUP (H110). 0.8" long, 0.4" slick sided drive band, HT isocore w/ 0.5 Cu. Chamber neck is 0.333, neck turned to 0.011, loaded neck dia 0.330, boolit sized 0.3085. Not HV but high pressure. Shot from 18" 1:10 AR. loaded 4 at a time in the mag. Yes there were flyers but the 'good' group is somewhat circular which indicates to me a 'non-perfect' base or imbalance in the boolit. Love to have that guy's gyro setup to watch nutation, or at least a drill press to see if I can make the base better. It's a custom barrel so I assume SAAMI spec chamber. Lee sizing die, mouth flared a tad, range pickup/converted brass. I don't expect it to be anything over 150yd load. No bragging, just info. My point is it's just mediocre stuff.

[vzerone]

157573
For what it is worth, chronyd @ 2112 fps. Plain base 145gr. 300BO loaded to ~40K CUP (H110). 0.8" long, 0.4" slick sided drive band, HT isocore w/ 0.5 Cu. Chamber neck is 0.333, neck turned to 0.011, loaded neck dia 0.330, boolit sized 0.3085. Not HV but high pressure. Shot from 18" 1:10 AR. loaded 4 at a time in the mag. Yes there were flyers but the 'good' group is somewhat circular which indicates to me a 'non-perfect' base or imbalance in the boolit. Love to have that guy's gyro setup to watch nutation, or at least a drill press to see if I can make the base better. It's a custom barrel so I assume SAAMI spec chamber. Lee sizing die, mouth flared a tad, range pickup/converted brass. I don't expect it to be anything over 150yd load. No bragging, just info. My point is it's just mediocre stuff.

When seated where is the base of the bullet in relation to the base of the neck?

[geargnasher]

Geargnasher about that getting accuracy without having to use thick necks....just think about it. Think about what the thicker necks are doing. Then think about what you have to do to get there without the thick necks.


Thought about it lots and lots and done all sorts of experiments. Closest I came to solving the issue created another one. Had Accurate cut a mould with no rear band and make it so just the gas check was in the neck. I only shot it in my M1A, and only to about 2200 fps, it grouped ok but not real tight. The issue it seemed to create was loss of bearing surface. I never messed with it any more but plan to do a lot of work with it in one of my bolt rifles this year, along with some other work with regard to this very thing.

How are YOU doing to help your shooting with rifles that have a lot of neck clearance?

Gear

[runfiverun]

35.
I know I have posted pics or links to pics [okay littlegirl did it] of the rcbs 30-165 silh boolit being shot at 1900+ fps.
the groups are actually very, very good.
the key to shrinking groups for me was all in the nose fitment and making an alloy capable of making the nose do it's job.
those long bore rider boolits rely totally on the nose doing it's job.
the base bands pretty much hold the gas back and plug the groove diameter.
the nose takes the twist and sets the tone as far as straight.

your gonna get accuracy a little more accuracy then usually a bit better accuracy then it's gone and trouble starts.
funny it's usualy right at the threshold.
stepping up to something like the rcbs 30-165 fngc takes things another step up the ladder.
now compare the two boolits side by side.
what do you see?
pretty much the rcbs silh boolit with more drive bands tacked onto it and a slight nose shape change.
suddenly you go from about 1900 fps up to about 2100 fps and changed nothing that really needs changing on the boolit to move the wall forward again.
the alloy for the second boolit was the firsts alloy cut in half with pure lead so going harder isn't the correct answer.

[vzerone]

Thought about it lots and lots and done all sorts of experiments. Closest I came to solving the issue created another one. Had Accurate cut a mould with no rear band and make it so just the gas check was in the neck. I only shot it in my M1A, and only to about 2200 fps, it grouped ok but not real tight. The issue it seemed to create was loss of bearing surface. I never messed with it any more but plan to do a lot of work with it in one of my bolt rifles this year, along with some other work with regard to this very thing.

How are YOU doing to help your shooting with rifles that have a lot of neck clearance?

Gear

I'm doing very well with it. That's interesting about your bullet failing. When you said it lost bearing surface are you saying after firing and examined the recovered bullet that is got much shorter?

[popper]

Just at the shoulder, which there is not much of. Actually bottom of the neck. Probably >90% fill. I've tried 4227 and will try some 1680 next but I haven't seen any difference yet. My point is that with mediocre equipment, mediocre skill I get what seems to be better than mediocre results. We're missing something? I haven't won the lottery so I'm not that 'lucky'. Oh, these are powder coated.

[vzerone]

Just at the shoulder, which there is not much of. Actually bottom of the neck. Probably >90% fill. I've tried 4227 and will try some 1680 next but I haven't seen any difference yet. My point is that with mediocre equipment, mediocre skill I get what seems to be better than mediocre results. We're missing something? I haven't won the lottery so I'm not that 'lucky'. Oh, these are powder coated.

Popper I was just wondering if you could cut some discs from the top of a Folgers coffee can and use one or two of them under your bullet. Being a flat base bullet it may help. Maybe be able to seat your bullet out a disc thickness as one can work too. I'm not sure if your problem is like you said the bases aren't square or not. Anyways I want to see if protecting your bases will help any.

[popper]

I think a friend has a drill press so I can see if burnishing the bases at a small angle makes them uniform, don't really have to be flat, just uniform. I'm pushing 170 gr GC close to same design to 2700 in 308 with similar results. I have the same mould but L.G.'d and PC'd, don't see any major difference - with my shooting skill. So IMHO large drive area doesn't seem to make a lot of difference. I'm not disappointed with my results, just surprised.

[geargnasher]

I'm doing very well with it. That's interesting about your bullet failing. When you said it lost bearing surface are you saying after firing and examined the recovered bullet that is got much shorter?

I mean the concept of making a bullet that basically fits 90% into the throat eliminates all but one real full-diameter bearing band, the loss was by design.

What are you doing to deal with excess neck clearance?

Gear

[vzerone]

I mean the concept of making a bullet that basically fits 90% into the throat eliminates all but one real full-diameter bearing band, the loss was by design.

What are you doing to deal with excess neck clearance?

Gear

Geargnasher I learned how to do it off the same two guys you tried to learn it from. You know who they are.

On you're bullet we're discussing here, I've see the diagram of it. Here's what I think. That's a long gas check shank. I assume it has a thin coat of lube on it from lubing/sizing. I don't see much contact from the bullet in the case neck, mainly the check at the rear and perhaps little of the bearing ban at the mouth. Contrary to many beliefs if that bullet does get bumped up it's not really happening until it's in the bore. I don't believe it's immediate in the throat. I see all kind of misalignment with that design and I also have to wonder how often the gas check comes off the bullet. Think about it. If it bumps up in the bore, the lube on that exposed portion of the shank keeps it from fully obturating and that gas check is all by itself on the back end.

[geargnasher]

Well, that ends that.

Gear

[44man]

I never tried to go too fast because I have no rifles to work with except my Swede but never made a mold for. I do have a Marlin or Remlin in 30-30 that I made molds for. I cut the cherries by eye, no designs or drawings. I like a GG above the check too.
I found my WDWW boolits not as good as WW with 25% pure are better. Still WD.
The boolit is 187 gr and I shot these groups at 100 yards. Top is 100% WW, bottom is 75%-25%. Varget powder. I am over 1900 fps. I will not push in the lever gun. Soon we will test in a friends 06's.
The boolit is .301" nose and .311" drive so it might need changed for the O6. I have lapped .30 dies for anything.
My boolit is right at the bottom of the neck and I did not figure for it, just pure luck.
It will be interesting to see what we can get. I also have a boolit at 193 gr to test.
But guys, who ever had a lever gun do this? 157737

[44man]

Everything I do is against the book. Even my best big bore PB revolver boolits only have .080" base bands. One hole groups at 50 and shotgun shells at 100.
I violate everything in print. It is feel and looks to a boolit.
I can't profess to say why some things work and others fail but I never met a factory boolit or mold that will out shoot mine in any caliber.
I can't draw a boolit or measure expanders, necks or all the nit picking stuff. Things work or fail and only shooting will show either.
I have sent friends my boolits to copy and ALWAYS something was changed so when I was sent some to test, they did good but never matched mine. Why would you change anything?
I read what most of you say a boolit must be and chuckle. You only get a star for effort.

[runfiverun]

Jim,,, we are just saying what we use to get there too.
I can assure you Gears boolits and mine are not the same, the alloy might be close nuff actually close nuff to yours too.
but from there we do things a little bit differently because we use a different design.
we still have to go through the gyrations to find the centerline of the barrel etc, but from there we tend to wander off in different directions on load details, alloy manipulations and some design features.

neither is right nor is either one of us right [see what I done there] but we both still get to our end goal.

[vzerone]

I never tried to go too fast because I have no rifles to work with except my Swede but never made a mold for. I do have a Marlin or Remlin in 30-30 that I made molds for. I cut the cherries by eye, no designs or drawings. I like a GG above the check too.
I found my WDWW boolits not as good as WW with 25% pure are better. Still WD.
The boolit is 187 gr and I shot these groups at 100 yards. Top is 100% WW, bottom is 75%-25%. Varget powder. I am over 1900 fps. I will not push in the lever gun. Soon we will test in a friends 06's.
The boolit is .301" nose and .311" drive so it might need changed for the O6. I have lapped .30 dies for anything.
My boolit is right at the bottom of the neck and I did not figure for it, just pure luck.
It will be interesting to see what we can get. I also have a boolit at 193 gr to test.
But guys, who ever had a lever gun do this? 157737

44man, that is some mighty nice shooting. You asked who ever done that with a lever gun. I can't remember the details, but Geargnasher did. I think it was with a Marlin 30-30 and he shot something like a 1/2 inch ten shot group. I don't remember the other details such as velocity or anything. Geargnasher has done some pretty good stuff in the past. I hope he continues and continues to refine his abilities to cast, load, and shoot cast. Geargnasher please drop in and tell us about that levergun.

[geargnasher]

Jim,,, we are just saying what we use to get there too.
I can assure you Gears boolits and mine are not the same, the alloy might be close nuff actually close nuff to yours too.
but from there we do things a little bit differently because we use a different design.
we still have to go through the gyrations to find the centerline of the barrel etc, but from there we tend to wander off in different directions on load details, alloy manipulations and some design features.

neither is right nor is either one of us right [see what I done there] but we both still get to our end goal.

That is key. More than one way to skin the proverbial cat. Some things have to be accomplished to get good results, but lots of ways to accomplish them. Learning to get good results with more than one method really expands one's repertoire of techniques for tackling those particularly tough rifles.

Jim, I have gotten two leverguns to do that, with no modifications to the guns. It's all about fit, alloy, and powder. And lube! Lube was a big deal and really showed up at long range, tuning lube got that last half MOA under control.

Gear

[44man]

Well you know how I feel about gear and most of you. It is only new guys with no experience we must help. To be set in your ways from something read does not work and I learn from many here.
I am going to need help with cast shot faster.

[vzerone]

Jim, I read you loud and clear. I wasn't trying to make what you done less then what it is. You asked if anyone had done that with a lever gun. Well Geargnasher came to mind instantly. I was impressed with what he had done when I first read it.

[vzerone]

That is key. More than one way to skin the proverbial cat. Some things have to be accomplished to get good results, but lots of ways to accomplish them. Learning to get good results with more than one method really expands one's repertoire of techniques for tackling those particularly tough rifles.

Jim, I have gotten two leverguns to do that, with no modifications to the guns. It's all about fit, alloy, and powder. And lube! Lube was a big deal and really showed up at long range, tuning lube got that last half MOA under control.

Gear

Geargnasher, you and runfiverun are very right that there are more then one way to do that. We all shouldn't be hampered by rules that were set we had to do it with just a ternary alloy with no copper bearing bans, no paper patching, no sabots....just a plain gas check cast bullet?? I see any of those as accomplishments. With a good number of them you are equaling j-word bullets and much cheaper I may say. Speaking of which I want to see members post about copper bands, paper patched, and sabot loads. I find all that very interesting.

[44man]

I don't have the rifle experience with cast and admit it. My forte is revolvers.
I can make a rifle shoot with jacketed, my best a 1/4" group at 350 yards with a pre 64 W 70 in 220 swift. Balvar 24 scope. Best of the best at the time.
Cast in a rifle is a new game so I need more help here, Sadly most rifles are long gone. I did have a 71 that shot cast long ago. I was an *** to sell it.
Cast has a limit but I don't care about that, I want accuracy first. Of what use is 2400 fps if you don't have accuracy? I have only one cast rifle now, the Marlin so if gear can tell me more I am all ears.

[vzerone]

I don't have the rifle experience with cast and admit it. My forte is revolvers.
I can make a rifle shoot with jacketed, my best a 1/4" group at 350 yards with a pre 64 W 70 in 220 swift. Balvar 24 scope. Best of the best at the time.
Cast in a rifle is a new game so I need more help here, Sadly most rifles are long gone. I did have a 71 that shot cast long ago. I was an *** to sell it.
Cast has a limit but I don't care about that, I want accuracy first. Of what use is 2400 fps if you don't have accuracy? I have only one cast rifle now, the Marlin so if gear can tell me more I am all ears.

What rifle do you have now that you would want to try cast in?

[popper]

44man - my 336 30/30 MG doesn't do too well with cast as the barrel is tight in the ends and loose in the middle. It does well with hard GC and jacketed but SIL's 308MX does great - good barrel and ballard rifling. This is 1875 from 150gr. PB in MX. The gun shoots better than me. The BO was a 1:7 early testing, same boolit.
157772

[vzerone]

44man - my 336 30/30 MG doesn't do too well with cast as the barrel is tight in the ends and loose in the middle. It does well with hard GC and jacketed but SIL's 308MX does great - good barrel and ballard rifling. This is 1875 from 150gr. PB in MX. The gun shoots better than me. The BO was a 1:7 early testing, same boolit.
157772

Fire lap the breech end popper.

[geargnasher]

I don't have the rifle experience with cast and admit it. My forte is revolvers.
I can make a rifle shoot with jacketed, my best a 1/4" group at 350 yards with a pre 64 W 70 in 220 swift. Balvar 24 scope. Best of the best at the time.
Cast in a rifle is a new game so I need more help here, Sadly most rifles are long gone. I did have a 71 that shot cast long ago. I was an *** to sell it.
Cast has a limit but I don't care about that, I want accuracy first. Of what use is 2400 fps if you don't have accuracy? I have only one cast rifle now, the Marlin so if gear can tell me more I am all ears.

Everything has a limit, but surprisingly it's often not the guns themselves. Not too many people have gotten a Marlin to put five into 3/4" at any velocity, much less 1900 fps. I was doing a little more at around 2150 or so, and also using a few cheats like buffer, a 3x9x44 scope, and a Forster BR seating die. Trigger still sucks at 7.5 lbs, though. I been called a lot of unpleasant things for posting about it so I have limited a lot of the discussions of the sort to a few friends who mostly don't think stuff like that is unusual, but I've done it and that proved to me the few others who've done it aren't full of bull. Sometimes folks have to do it themselves to believe what is possible. I would NEVER have thought a revolver could shoot MOA at extended ranges, but you and Rick blew me away. Next thing you know I'm learning from what you posted and getting near enough to that myself to see it, knowing my shooting ability (skills) is the limiting factor, not the revolver or the loads. Just amazing what a person can learn to do with cast bullets if they don't start out with a bunch of pre-conceived notions about what they cannot do.

Gear

[vzerone]

Everything has a limit, but surprisingly it's often not the guns themselves. Not too many people have gotten a Marlin to put five into 3/4" at any velocity, much less 1900 fps. I was doing a little more at around 2150 or so, and also using a few cheats like buffer, a 3x9x44 scope, and a Forster BR seating die. Trigger still sucks at 7.5 lbs, though. I been called a lot of unpleasant things for posting about it so I have limited a lot of the discussions of the sort to a few friends who mostly don't think stuff like that is unusual, but I've done it and that proved to me the few others who've done it aren't full of bull. Sometimes folks have to do it themselves to believe what is possible. I would NEVER have thought a revolver could shoot MOA at extended ranges, but you and Rick blew me away. Next thing you know I'm learning from what you posted and getting near enough to that myself to see it, knowing my shooting ability (skills) is the limiting factor, not the revolver or the loads. Just amazing what a person can learn to do with cast bullets if they don't start out with a bunch of pre-conceived notions about what they cannot do.

Gear

You've done very well with your lever actions. Things apparently are changing here in the Castboolit forum so I don't think you have to worry talking about your endeavors now.

[geargnasher]

You've done very well with your lever actions. Things apparently are changing here in the Castboolit forum so I don't think you have to worry talking about your endeavors now.

Funny, I thought about making the same observation to you, but you didn't seem very open to discussing the HOW. I'd like to see a lot more discussion of "how" here, there's been a huge void of info for a long time about pushing the envelope of cast bullets with normal rifles and heaven knows I for one can use all the help I can get and am sure others feel the same.

Gear

[vzerone]

Funny, I thought about making the same observation to you, but you didn't seem very open to discussing the HOW. I'd like to see a lot more discussion of "how" here, there's been a huge void of info for a long time about pushing the envelope of cast bullets with normal rifles and heaven knows I for one can use all the help I can get and am sure others feel the same.

Gear

Well tell me, how to you fit the rest of your case from after the neck back? What dies are you using, type that is, not brand. All the brands make the different types except maybe LEE.

[44man]

Neck sizing alone does not work good in a lever gun and in any rifle, brass will eventually need FL again.
I use the regular Hornady size die and raise it just enough to allow chambering in the Marlin but my brass will not fit a friends 94 so I need to FL for his.
Even if you use collar dies, eventually you will need to set the shoulders back again. Using the Lee collet sizer will be the same so you also need regular dies instead of using the bolt and lugs to set shoulders back.
My 30-30 brass grows fast due to spring of the bolt so I need to trim a tad every firing.
Even with the small amount of turning on the necks still gives me a straight chambering along with the nose riding the lands. No need to worry about cases laying down in the chamber if you get fit.
Fitting brass to your gun allows the shoulder to center brass unless you have run out. Get rid of all run out, you need less then .002". Goes the same with jacketed.
Once you get fit, more velocity can be had.
For best accuracy, sort brass by where the boolits hit. Sadly I am lax here and mine gets mixed up. I know better but fail. Same in my revolvers, brass gets mixed up.
No matter what you do, brass is what causes so many bad groups. I am going to put a scratch on the case head of all brass that goes in the group. Pouring all my brass in the tumbler does me no favors.

[geargnasher]

Well tell me, how to you fit the rest of your case from after the neck back? What dies are you using, type that is, not brand. All the brands make the different types except maybe LEE.

Two different dies, both RCBS. One is a Gold Medal Match FL die with neck bushings, other is also a neck die with shoulder bump feature used about every 3-5 firings to knock the shoulder back about .005". I fit the cases close to the chamber with minimal case body sizing after firing.

Gear

[vzerone]

Two different dies, both RCBS. One is a Gold Medal Match FL die with neck bushings, other is also a neck die with shoulder bump feature used about every 3-5 firings to knock the shoulder back about .005". I fit the cases close to the chamber with minimal case body sizing after firing.

Gear


I use a neck bushing die with the shoulder bump feature and I have it set so it just kisses the shoulder each time. I found the neck sizing dies only wanting in comparison. Sounds your brass is not the problem so that leaves your load, loading, and bullet.

[popper]

Fire lap the breech end It's MG so I'm not sure I want to try. It shoots FTX fine. When I slugged it, the slug almost falls through to the breech end. Late model before Remlin.

[vzerone]

It's MG so I'm not sure I want to try. It shoots FTX fine. When I slugged it, the slug almost falls through to the breech end. Late model before Remlin.

popper it may be like some of the S&W revolvers. Where the barrel screws into the frame the bore gets restricted because of the tight thread crush and it's only a little bit to lap out. Might be the same on your rifle. Any way you can slug from the breech and see how far the slug goes when it gets loose?