Stripping: Are you part of the problem?

[Bass Ackward]

Is your bullet stripping? Ok, is it velocity related or is it mechanically caused? This determines your final sizing diameter needed for your slugs. The cause for stripping is important to know. It will drive how hard of a bullet that you actually need to shoot with a specific bullet design and at what size you may need to size.

So …. do hard bullets strip less than soft? The answer is maybe and in some cases, stripping can be worse the harder that you go. You must determine if your stripping is velocity related or is it mechanical? Question is, how?

Every person should invest in a Lee sizer of your barrel’s groove diameter whether or not it is a rifle or handgun. Then you should manually size exactly what you intend to shoot exactly to the size your barrel will shoot it. As bullet diameter goes up and encounters resistance, try to simulate rifling by gripping the base with vise grips and rotating it in the Lee die. If you can’t over come the friction, your rifling won’t be able to either. For those that like to water drop, feel what your bore feels as it sizes and engraves at peak hardness.

I spent some time lately watching Babbitt bearings (30 BHN) pressed into holes that were undersize by .0005 and then .001 watching the amount of force (measured in tons) required to press the bearing into place. Elmer always said that if you were in the larger bore diameters such as 44 or 45s that you could be .003 or .004 over groove and still be OK as compared to 35 / 38 caliber where you needed to be spot on. That does not always prove out and will definitely give you fits sizing in a press. In fact, the exact opposite will be true if you like hard slugs. Smaller bores are more friendly to sizing over diameter slugs. This will be observed with sizing different diameter, hard slugs on your loading press using the Lee sizers. Shorter (lighter) slugs also will reduce friction. But quite simply, the larger the hole, the more force is required to press in something larger than the hole itself if the bullets hardness proves counter productive.

Your barrel is nothing but a rotational sizer if you shoot larger than groove diameter. The question is, does the rifling try to rotate the slug before the sizing step is complete? If it does, then you will push the bullet straight ahead until the rotation force is great enough to over come the friction from the sizing operation, thus creating mechanical stripping. Think about that for a minute. This may very well be the reason behind 50/50 WW and pure as the outside hardens more than the core making it easier to size while still holding the rifling.

Why is this important to know? Because sizing can and often will determine the bullet hardness that will perform best over all. And …. There is no constant between calibers, bore conditions, velocity levels unless you eliminate it and size to bore. This explains gross examples of stripping with very hard slugs as observed by Jimmy. And the complication is: the “smoother” the steel surface, the more friction will be encountered during sizing. It’s easy to verify this by smoothing your sizing die as Lee’s are generally rough. And so as a barrel smooths up over time, or wears in, why things can change from what you observed before when you developed your load at a certain diameter.

This is what the Lee bore diameter sizer will teach. And from it comes the solution. Just as LLA can aid in sizing, it will reduce the friction for rotational effort, thus minimizing mechanical stripping. So use this logic and a light coat of LLA over what ever lube you are using at the same exact loads you have been shooting and see if groups improve. If they do, then you are shooting too large of diameter bullets for that bullet design, velocity level, and hardness combination in the life cycle stage of “that” barrel at THAT point in time. If the groups don’t improve, then you may very well see group improvement with a harder, or larger diameter slug that could be softer than you are currently using.

I have long believed that the faster I wanted to go, the harder I needed to be and the smaller I needed to size but I never was able to prove it to myself for each bore diameter and bullet design until now. With various gun conditions and rifling types, it is easy to see why we get so many different recommendations for bullet hardness as to what shoots for us.

I suppose that this is why Lyman recommended for decades that you size bore diameter or no more than .001 over bore. Of coarse, this is all altered by bullet jump, rifling height, twist rate, forcing cone angle, bore wear / condition, width of drive bands on the slug, quality of bullet lube, and on and on with all the things we discuss daily when shooting. The delicate balance is that bullet diameter has to be balanced between what is required not to lead the throats. (keep lube on the slug)

So from this it should be obvious why various stages of barrel wear or break-in can and does affect what you observe from recovery of fired slugs showing stripping. Learn to understand what you see so that you can adjust (correct) for best results.

[Cherokee]

Thanks, hadn't though about that. So much good info on this forum.

[303Guy]

Thanks, Bass Ackward. Lots of food for thought there. I know I will have to re-read you post so's to digest what you have said. Firstly, I want to relate to my own observations and experience. My milage is going to differ - after all, I drive differently and my 'car' is in different condition (pretty crappy, actually). Mmmm.... ! In a similar vain, I found, quite unexpectadly, that my rust damaged two-groove bore, 303 Lee Enfield is very accurate and does not copper foul the bore. (Hopeless with cast or paper patched boolits, due to the rough driving edge of the rifling grooves).

You mentioned 'tons of force'. Well, my Lee Enfields are rated at 19 tons per square inch and that's a moderate pressure rifle.

[armyrat1970]

Whoa! Lot of info there at one time. As 303Guy stated, I may have to re-read this a few times before I can fully appreciate it.
Thanks for the info and thoughts.

[Lloyd Smale]

I have to agree with bass. At least i think im agreeing. Ive never had luck with unsized bullets or oversized ones in guns with proper dimentions. Bore size or a .001 over allways did better.

[fatelvis]

[QUOTE][the “smoother” the steel surface, the more friction will be encountered during sizing./QUOTE]

Good reading, and seems to make sense. I do not, however, agree with the above quote, regardless of the "sizer experiment".

[Bret4207]

Once again I'm pretty much on board with Bass. Particularly the sentence, "Then you should manually size exactly what you intend to shoot exactly to the size your barrel will shoot it." This is where the "kick it hard and make it obturate" crowd and I part ways. Better to fit the boolit to the throat and give it a gentle boost than beat it into shape. I also agree with the "bigger takes more power" idea. Makes sense, more surface area+ more friction to overcome.

Good job Bass.

[LeadThrower]

The breadth of knowledge here never ceases to amaze me! Thanks Bass!

[303Guy]

the “smoother” the steel surface, the more friction will be encountered during sizing.
Could be due a rough surface that's been partially polished will carry lube in the troughs. Also, there will be a smaller surface contact area. Just a thought.

[armyrat1970]

Could be due a rough surface that's been partially polished will carry lube in the troughs. Also, there will be a smaller surface contact area. Just a thought.

Was thinking about that myself. I always thought the smoother the surface, the less amount of friction.

[fatelvis]

I look at it in terms of:
Is it easier to pull a peice of flat stock steel tied to a rope, over 120 grit sandpaper, or plate glass? Would lubing the sandpaper and glass make much difference? Wouldn't they both give less resistance with the lube, in a relative manner? Just my way of thinking. I'm not saying if it's right or wrong...

[44man]

Bass is thinking hard again! :bigsmyl2: Gee, I need to find a greeter job for him at Wally World. [smilie=l:
This is not a simple problem or a simple solution. Most want to cure leading and if you get it it is a mechanical problem first. That means alloy and/or skid but not always. I can shoot a 50-50 alloy and get zero leading, none, zip, but groups open and I get fliers. Recovered boolits show a lot of skid but for some reason, no gas cutting or leading.
Too hard can leave small strips of leading yet super accuracy and by reducing the hardness or changing the alloy it does not reduce accuracy and might improve it and stop leading, too soft will fail with more skidding. Real soft will fill the bore with lead.
What is in the actual alloy can alter everything, even one batch of WW's can drive you nuts while another is perfect.
You can have some leading with the best accuracy and no leading with poor accuracy and the other way around too.
My one revolver has almost 60,000 rounds and the barrel is so smooth it does not even pick up copper, yet it still shoots the same alloy the best just like it did the day it was new. It WILL lead with soft boolits and give me fliers.
BHN is a misnomer anyway with all kinds of alloys reading the same hardness.
I can't in good faith sit here and tell you that twisting a boolit in a size die will tell you what it will do in your gun. I will not try and tell you what the coefficient of friction between all alloys and your barrel steel is. I will not try and tell you what alloy or hardness will stop skid. I will not tell you what you need with larger bores and heavier boolits. I will not tell you what alloy is needed for fast or slow powders.
The reason is the NONE OF US HAS THE SAME LEAD! I don't even have the same lead when I pull ingots out of the box.
When I recover boolits and see skid, I just make the alloy HARDER, not softer since I can not slow the burn rate and the only control I have is the alloy.
I just can't think backwards, assuming a softer boolit will not skid with the same load. Two alloys of the same hardness can have one skid and the other will not. But going harder with the skidding boolit has always worked.
Neither will I tell you one size boolit will not skid but a larger one will or the other way around. I shoot from exact groove size to way over with no change because the alloy is in control.
Hardness is a funny thing because it does not tell us what is in the lead. Brittle is no good because lead can break off when trying to engage the rifling. It can shatter in game. Soft will not engage the rifling.
Take a boolit of a given hardness and by fooling with the brass and loads you might make it work but when you use your best loads, the only thing else you have is to alter the alloy to match the load. That is my method, I will not use a poor load to make the wrong boolit shoot because it is never a good load.
The cure of course, is to only shoot a jacketed bullet.

[44man]

I suppose that this is why Lyman recommended for decades that you size bore diameter or no more than .001 over bore.

In the above did you mean to write BORE or groove diameter ?
thanks,
We are all guilty of that at one time or another. It always means groove size unless you are talking about bore ride.

[Multigunner]

Could be due a rough surface that's been partially polished will carry lube in the troughs. Also, there will be a smaller surface contact area. Just a thought.

Tests run in the 1840's on barrels with varying degress of bore surface finish indicated that friction was greater when the bore was highly polished.
Similar experiments of the turn of the century indicated that when lead bullets were used in a bore that was "seasoned" by microscopic pits the tiny pits held globules of bullet lubricants that acted as liquid ball bearings under pressure, allowing noticable increases in velocity over the same loads fired in a new well polished bore.
Higher pressures, temperatures, and velocities of more modern cartridges seem to reverse that effect.




We are all guilty of that at one time or another. It always means groove size unless you are talking about bore ride.
The nomenclature used by the British seems better suited to describing the bore and groove situation. They call the central bore dimension the "Minor Diameter" and the invisble circle encompassing the depth of the groove the "Major Diameter". Easier to envision especially when an unequal number of grooves are used.

A case cited in forensic examination of bullets tells of a .22 bullet known to have been fired by a weapon not matching bullets of the same brand fired from the same rifle in comparasion.
In that case excessive grease in the bore had caused bullet skid, the lands being more narrow than when a second bullet was fired after the first had burned away the excess grease.

[StarMetal]

I look at it in terms of:
Is it easier to pull a peice of flat stock steel tied to a rope, over 120 grit sandpaper, or plate glass? Would lubing the sandpaper and glass make much difference? Wouldn't they both give less resistance with the lube, in a relative manner? Just my way of thinking. I'm not saying if it's right or wrong...

That's not a good example. Sandpaper is design is to cut into a surface. Better example would be a flat smooth steel surface and the same steel with rounded humps of great radius. Slide the flat steel over those two and see which offered less resistance. The smoother the steel surface is the more molecules of the steel come into contact with what is sliding over it. Friction surfaces like flywheel faces in clutch systems or brake drum, or disc rotor...they are super smooth, not rough to provider more surface to grab to grab too.

There are differences of cohesion between unlubed metals against one another.

I believe it was Ackley that said once the engraving of an oversized bullet is accomplished the friction and pressure drop a lot. I believe he said firing a 30-06 bullet through a 6.5 bore had high pressure and friction until it got sized down/engrave and that after that he said it actually had less pressure then the norm 6.5 bullet. Something to that effect.

[303Guy]

Thanks, 44man. Just when I thought I was getting a handle on one small aspect ... :mrgreen:

Actually, I have been pondering the various properties of alloys and wondering how I might quantify/qualify them. Surface hardness, compressablility, ductility. maleability, bendability, springyness ... There must be some tests one can do to compare an unknown alloy to one that is known to work for us! For example, if one were to cast an alloy and measure its BHN then swage that casting then remeasure the BHN, there will be a change, right? Would the degree of change give a clue as the properties of that alloy? Different alloys of the same BHN, would surely have different 'flow' points under pressure, right? We could measure that.

I've mentioned before about one boolit that appeared to twist in a plane just ahead of the case mouth. I'm guessing it went plastic in that zone under the force of accelleration and lateral upset due to a coincidental casting crease at that spot.

[303Guy]

Better example would be a flat smooth steel surface and the same steel with rounded humps of great radius. Slide the flat steel over those two and see which offered less resistance. Then again, consider a smooth steel surface with random rust pits in it. The major surface is still flat but now there are troughs instead of lumps. That's sort of what you get when you fire-lapp a rust damaged or otherwise rough bore.

[Multigunner]

Then again, consider a smooth steel surface with random rust pits in it. The major surface is still flat but now there are troughs instead of lumps. That's sort of what you get when you fire-lapp a rust damaged or otherwise rough bore.

Thats pretty much how it works.
In abused military bores pitting is usually not simply a matter of rust alone, high velocity impacts of superheated particulates can leave star shaped craters with turned up edges. Lapping can't usually remove all trace without making the bore oversized but it can dull the edges of the pits so instead of scraping the bullet surface the pit holds oils which help the bullet surface ride over the pit rather than digging in.

[Bass Ackward]

Tests run in the 1840's on barrels with varying degress of bore surface finish indicated that friction was greater when the bore was highly polished.



Absolutely. Old Timers used to have their guns refreshed or roughed up to use lead. It has also been known for years that cut rifling was the best form of rifling for lead. All because it avoided galling from direct lead to steel contact. Or .... leading from lead steel contact above the lubrication threshold which is defined by your lube.

Some people believe that " ALL " leading is caused by gas cutting when in fact, most gas cutting comes from lead displaced by galled lead (fouling) first.

As to the gentleman asking about terms. Bore diameter is correct to define a bore diameter such as the 308 or 458 bore. So .001 over bore is correct for a general reference to any bore diameter. If you focus on a single caliber or barrel, then bore and groove are applicable definitions for that particular tube.

The whole point of this post was to explain why one guy observes stripping at 30 BHN and incorrectly assumes that " ALL " stripping is 100% velocity / hardness related when a guy can shoot soft and see absolutely no frontal stripping at the same velocity level.

Which hardness that produces the best accuracy is NOT because of the stripping that occurs on the front end, but on the rear end as it leaves the muzzle that affects the launch. Frontal stripping, that causes NO loss of bore center, is immaterial to accuracy.

Maybe you should read that again. This is why you some see great accuracy even though the front shows stripping. And it is also why some guys can shoot soft and still produce good handgun accuracy. And also that as a barrel smooths from age, that hard may turn out to be the only method that can prevent stripping from smooth steel contact.

In the end, do what you gotta do to get holes close to one another. Accuracy is all in the launch.

I am working on a new Ruger Bisley 44 Special (actually 3 as part of a wear test I am conducting, but only one belongs to me).

The best accuracy so far has come from rock hard, 34 BHN bullets sized to .430 at 575 fps using 3.4 grains of bullseye.

The best HV loading is coming from 8 BHN using 19 grains of 4227 and 20-1 sized .4315 using the group buy 240 grain olgival plinker that Bob did.

The bore on this gun is embarrassing and looks like it was cut out with a chain saw. But the darn thing shoots. Guarantee that there is NO POSSIBLE WAY for a 100% seal. No way that there could be. But it just don't seem to matter. It leads and it shoots.

Sort of Bass Ackward again huh? But that is the way it is.

[Multigunner]

My old S&W Model 37 was a basket case I rebuilt, bought from a guy that found it buried in mud when the lake level dropped. Grips had rotted away and all nickel on the frame and early production aluminum alloy cylinder had turned to a crust that could be scraped off with a finger nail, but the barrel was chromed.

There was a large rusted patch in the bore about 5/8" long near the muzzle on one side, the rest of the bore was clear and bright.

I expected the bore to lead up at that rusted patch, but it never did, and accuracy was suprizingly good with anything I put through it.

I traded it off when two chambers showed signs of expanding under normal pressures, a common problem of the aluminum cylinders and why they recalled them to be replaced with steel cylinders.

[StarMetal]

Absolutely. Old Timers used to have their guns refreshed or roughed up to use lead. It has also been known for years that cut rifling was the best form of rifling for lead. All because it avoided galling from direct lead to steel contact. Or .... leading from lead steel contact above the lubrication threshold which is defined by your lube.

Some people believe that " ALL " leading is caused by gas cutting when in fact, most gas cutting comes from lead displaced by galled lead (fouling) first.

As to the gentleman asking about terms. Bore diameter is correct to define a bore diameter such as the 308 or 458 bore. So .001 over bore is correct for a general reference to any bore diameter. If you focus on a single caliber or barrel, then bore and groove are applicable definitions for that particular tube.

The whole point of this post was to explain why one guy observes stripping at 30 BHN and incorrectly assumes that " ALL " stripping is 100% velocity / hardness related when a guy can shoot soft and see absolutely no frontal stripping at the same velocity level.

Which hardness that produces the best accuracy is NOT because of the stripping that occurs on the front end, but on the rear end as it leaves the muzzle that affects the launch. Frontal stripping, that causes NO loss of bore center, is immaterial to accuracy.

Maybe you should read that again. This is why you some see great accuracy even though the front shows stripping. And it is also why some guys can shoot soft and still produce good handgun accuracy. And also that as a barrel smooths from age, that hard may turn out to be the only method that can prevent stripping from smooth steel contact.

In the end, do what you gotta do to get holes close to one another. Accuracy is all in the launch.

I am working on a new Ruger Bisley 44 Special (actually 3 as part of a wear test I am conducting, but only one belongs to me).

The best accuracy so far has come from rock hard, 34 BHN bullets sized to .430 at 575 fps using 3.4 grains of bullseye.

The best HV loading is coming from 8 BHN using 19 grains of 4227 and 20-1 sized .4315 using the group buy 240 grain olgival plinker that Bob did.

The bore on this gun is embarrassing and looks like it was cut out with a chain saw. But the darn thing shoots. Guarantee that there is NO POSSIBLE WAY for a 100% seal. No way that there could be. But it just don't seem to matter. It leads and it shoots.

Sort of Bass Ackward again huh? But that is the way it is.

Bass,

I've recovered lots of rifle bullets shot at high velocity in fast twist barrels, not only in dirt, but in my water tank bullet stopper. Never have I ever found stripping at the rear of the bullet upon leaving the muzzle. All I've ever found was fining on the pressure side of the land at the muzzle and I sent you the picture of that bullet which was fired from a 8x56R M95 Steyr. I'd like to see some good pictures of bullets that you have claim have that. Heck Bass with a really stout jacketed rifle load even that last little tiny bit of the base of the bullet still in the muzzle would strip too and it's just not happening. Like in Mythbusters I call this one busted. Not buying it.

[Frozone]

I also agree with the "bigger takes more power" idea. Makes sense, more surface area+ more friction to overcome.

No, it's the other way around.
It's easier for the pressure in the barrel to size a larger bullet than a smaller, assuming a similar bearing surface length .

Why? the pressure is pushing on the base of the bullet - the pressure on a 2" circle is 4 times the pressure pushing a 1" circle. While the bearing surface area is only doubled! It's twice as hard to size a bullet half the size by firing it. Surprise Kieth was right!

[44man]

Absolutely. Old Timers used to have their guns refreshed or roughed up to use lead. It has also been known for years that cut rifling was the best form of rifling for lead. All because it avoided galling from direct lead to steel contact. Or .... leading from lead steel contact above the lubrication threshold which is defined by your lube.

Some people believe that " ALL " leading is caused by gas cutting when in fact, most gas cutting comes from lead displaced by galled lead (fouling) first.

As to the gentleman asking about terms. Bore diameter is correct to define a bore diameter such as the 308 or 458 bore. So .001 over bore is correct for a general reference to any bore diameter. If you focus on a single caliber or barrel, then bore and groove are applicable definitions for that particular tube.

The whole point of this post was to explain why one guy observes stripping at 30 BHN and incorrectly assumes that " ALL " stripping is 100% velocity / hardness related when a guy can shoot soft and see absolutely no frontal stripping at the same velocity level.

Which hardness that produces the best accuracy is NOT because of the stripping that occurs on the front end, but on the rear end as it leaves the muzzle that affects the launch. Frontal stripping, that causes NO loss of bore center, is immaterial to accuracy.

Maybe you should read that again. This is why you some see great accuracy even though the front shows stripping. And it is also why some guys can shoot soft and still produce good handgun accuracy. And also that as a barrel smooths from age, that hard may turn out to be the only method that can prevent stripping from smooth steel contact.

In the end, do what you gotta do to get holes close to one another. Accuracy is all in the launch.

I am working on a new Ruger Bisley 44 Special (actually 3 as part of a wear test I am conducting, but only one belongs to me).

The best accuracy so far has come from rock hard, 34 BHN bullets sized to .430 at 575 fps using 3.4 grains of bullseye.

The best HV loading is coming from 8 BHN using 19 grains of 4227 and 20-1 sized .4315 using the group buy 240 grain olgival plinker that Bob did.

The bore on this gun is embarrassing and looks like it was cut out with a chain saw. But the darn thing shoots. Guarantee that there is NO POSSIBLE WAY for a 100% seal. No way that there could be. But it just don't seem to matter. It leads and it shoots.

Sort of Bass Ackward again huh? But that is the way it is.
We start to agree. The worst thing with a round ball muzzle loader is a "shot smooth" bore. Old timers would fill the bore with urine to etch it. I use vinegar over night.
You are correct that front boolit skid does not matter but you have to back up for the place base band seal is important and that is at the rear of the barrel, not the muzzle.

[Bass Ackward]

Bass,

I've recovered lots of rifle bullets shot at high velocity in fast twist barrels, not only in dirt, but in my water tank bullet stopper. Never have I ever found stripping at the rear of the bullet upon leaving the muzzle. All I've ever found was fining on the pressure side of the land at the muzzle and I sent you the picture of that bullet which was fired from a 8x56R M95 Steyr. I'd like to see some good pictures of bullets that you have claim have that. Heck Bass with a really stout jacketed rifle load even that last little tiny bit of the base of the bullet still in the muzzle would strip too and it's just not happening. Like in Mythbusters I call this one busted. Not buying it.



I have. And you just described it. If you strip the check, then you have the lead body holding it all and you see it on the pressure side of the land. If you don't lose the steering wheel of the slug, all will be fine.

Especially found with molds that have tapered shanks for applying checks. Same with too hard of gas checks. Or too soft too. Or PB.

Not saying that it happens all the time or you couldn't get high velocity. But when it does, nothing that you can do will make a difference. And the harder you push from that point on, the worse it gets and the farther up the slug it will move.

[crabo]

How do you know if you are stripping? Do you have to have a recovered boolit to inspect or will there lead in the last part of your muzzle?

[Frozone]

How do you know if you are stripping?
There's a pole in front of you and someone is throwing dollar bills at you.

[JIMinPHX]

There is some related info in this post - http://castboolits.gunloads.com/showthread.php?t=81258

It will be old news to some people involved in this thread, because there are several posters here that are in that one as well.

[303Guy]

There's a pole in front of you and someone is throwing dollar bills at you. Good one! Straight from the hip.:Fire: Fast and unexpected!:bigsmyl2:

How important is this feathering on the pressure side? (Boolits - I'm talking boolits :mrgreen:).