Update: Plain based bullets... how fast can they go?

[w30wcf]

Fellow cast bullet enthusiasts,

In the previous thread: http://castboolits.gunloads.com/showthread.php?t=2379&page=1&pp=20 reference was made to Phil Sharpe's "Complete Guide To Handloading" (1937) wherein it was written that at the Hercules Experimental Station, they loaded 23.0 grs. of HiVel #3 back of a 150 gr. plain-base bullet and recorded 1,950 f.p.s. in the .30-30 Winchester.

As we know, that's pretty fast for a plain based bullet. No account was given regarding alloy, accuracy or fusion, leading the reader to believe that it was an accurate, trouble free plain based bullet load with some pizzaz.

Bullet #311241 was the likely one used since it was a bullet in the 150 gr. range that was popular at the time.

I finally had the opportunity recently to test the load in question. I molded bullets from Lyman #2 alloy (90/5/5) lubed them with 50/50 Alox/Beeswax and loaded them over 23 grs. of Hercules #3 in Winchester cases. CCI 200 primers were used.

I decided to use a .06" polyethylene wad under the bullets on 5 rounds and the other 5 rounds were loaded with nothing between the base of the bullet and the powder charge.

I used my Winchester 1894-1994 Centennial .30-30 rifle (26" barrel) for this test. I shot the cartridges containing the polyethylene base wads first. 5 rounds printed into a nice 1 1/4" group @ 50 yards with 3 of the rounds landing in 3/4". Average velocity for the string was 2,006 f.p.s. A nice start.

I then chambered a cartridge with the naked plain based bullet, aimed and fired. A check through the spotting scope indicated that the bullet had not made contact with the target. I chambered another cartridge, aimed and fired again with the same result. Hmmmm....... (That's kind of what I thought was going to happen.)

I then put up a bigger sheet of paper and the remaining 3 bullets landed into about a 10" group about 18" away at 1 o'clock from the bullet impacts using the polyethylene base wads.

So........either the Hercules Experimental station used base wads of some sort or the larger group achieved was "good enough" since the bullets were flying straight or......... they know something we don't.

If nothing else, at least in this test, plain based bullets can be made to shoot at higher velocities if the base is protected.

Sincerely,
w30wcf

[45 2.1]

You are mostly correct. The base must be protected in some way. If you have read Harvey Donaldson and others, you would see that graphite wads were very popular with jacketed and cast at that time period. Something that is little known now. There are other ways also. Merril Martin has experimented with moly coating via impact tumbling the graphite into the surface of plain based bullets. Good reading. If you try very slow powders, they will help the situation, especially in large cases. Another method is Freechecks which are possibly the easiest, cheapest solution to the velocity and accuracy problem. I Freecheck the 311241 in the 30-30 with very soft alloy. It makes a very good expanding bullet for field use and is very good on the target too. Try a harder bullet in your test and see what happens.

[Four Fingers of Death]

I've never seen an animal out run them.

[Papa smurf]

:veryconfu
What is a freecheck

[StarMetal]

John,

There's another thread describing the freecheck exactly. In a nutshell it's an aluminum disk cut from a pop or beer can that is swaged onto your plainbase bullet during the sizing/lubing operation, with slight modifications to your sizing die. The end results is sort of a little cup gascheck from aluminum. The disk does have to not only cover the base of course, it has to continue up the sides of the bullet also, not real far though. The powder gas does it's cutting up the sides of the bullet between the bullet and the bore.

Joe

[carpetman]

Not sure about a free check,but I think a Czechoslovakian abortion is a cancelled czech.

[DOUBLEJK]

WE ARE GEARING UP NOW... ED WOSIKA HAS LIT A FIRE UNDER MY TAIL TO GET THEM (FREECHECS) BACK ON THE MARKET... PROBABLY A MONTH OR TWO WHEN MY "day job" SLOWS WAY DOWN AND THE BOOK IS FINISHED... I WANT TO GET THE BOOK DONE FOR CHRISTMAS SHOPPERS.... PACO

[45 2.1]

The last time I saw prices for the Freecheck dies, they were over $100. I wonder what they will be now.

[castalott]

to get back to the original thought of the thread for a moment...

how fast will plain base bullets go?

I read somewhere that case capacity/expansion ratio has a great effect on plain base bullets. The example given was: 'Push a 311410 plain base hard (2000fps) in a 30-06 and you don't have much. The same bullet/velocity in a 30 carbine is usable. The difference is in the case...'

This is how I remember it anyway.....Anyone else read this and remember it different?

Dale

[Bent Ramrod]

I shoot cast in everything from .22 to .45. I can get about 1300 ft/sec with accuracy out of plain base bullets pretty routinely, sometimes up to 1450 ft/sec in some special cases. Anything above that needs gas checks, in my experience.

Of course, any bullet can be sent out at any velocity; I generally try for the best accuracy loads I can.

[andrew375]

I don't see how putting anything bits of plastic on the base of a bullet can have any influence on velocity or accuracy. As I see it the main contributions made by a gas check are to add tensile strength to the part that has to resist the greatest force applied by the driving powder gasses and give an even edge to the base to keep the gases in their place. The only contribution to this that can be made by a wad (of any kind) is to act as a gasket by being forced into any gaps around the edge of the bullet base to give a gas tight seal.

For long range, 600-1000 yards, loads for my .375H&H I use plain base bullets with a piece of 3/8 copper tube cast into the front driving band. Driven by 72 gr. of VV N140 gets me 2700 fps and accuracy as close to minute of angle as I can shoot. Without the copper driving band accuracy with this bullet falls off at over 1900 fps. The same bullet with a gas check heel gives superb accuracy at up to 2200 fps. Extensive testing by HandLoader staff of the Wilke gas check also bore out the fact that whatever gas checks do it has little to do with protecting the bullet base.

[StarMetal]

andrew,

Let's attack the velocity statement first. First any plastic, metal, whatever cup behind a bullet helps seal the gases better then if nothing was there and that means better performance, thus more velocity. Second adding any weight without changing the powder load increases pressure, thus increases velocity.

Now apparently you haven't dug alot of bullets out of the your backstop whatever that may be. Yes gaschecks do keep the base of the bullet square, they also keep the gas from cutting up the past the sides of the bullet. I've see gas cutting and I've see bases deformed by gas pressue and gas heat. Gaschecks do add some mechanical strenght to the alloy bullet to resist stripping in the rifling also. I can't understand how Wilkes gascheck company can't understand the mechanics of gaschecks. Why do they think they are called gaschecks for? If they were thought of as you think of them they would be called bullet strengtheners or base squarers , or something like that.

Joe

[45 2.1]

This has alot more to do with mechanical strength of the bullet alloy and what happens to the bearing part of the driving bands, especially the bottom one than most realize.

[tomf52]

Another argument for gas checks? I lke 'em!

[7br]

Yeah, what 45.2.1 said. Veral Smith threorized one of the functions of a gascheck to help keep the rifling from stripping the bullet. He likened it to putting a cloth between your hand and a stubborn jar lid. My experience is that my velocity in a .41 starts to fall off around 1250fps or so with a RCBS 210 Keith style bullet. (guestimate based on bullet weight and powder charge in a manual) Your mileage may vary.

[wmitty]

Andrew375 - Could You Give A Bit More Information Concerning Your Load For The .375 H&h ? I Am Also Loading Cast For This Round And Would Like To Know How You Cut The Tubing Short Enough To Fit Your Mould. Thanks!

[KCSO]

I have routinely loaded to 1600 fps in the 38-55 with good accuracy and no leading. I do use a slower burning powder for these loads. In the smaller calibers I really havent tried to push them over 1500. I do have a modified Lee 170 gr fp mould that casts a 175 plain base bullet. I may just try and see how high I can go wtih this one.

[andrew375]

Andrew375 - Could You Give A Bit More Information Concerning Your Load For The .375 H&h ? I Am Also Loading Cast For This Round And Would Like To Know How You Cut The Tubing Short Enough To Fit Your Mould. Thanks!

The bullet I use is the NEI 375-280-GC which has two wide driving bands. I simply use a plumbers tubing cutter fitted with a simple depth stop to cut the tube. To help production I use a lathe to slowly spin the tube, but it works fine by hand. I insert the ring into the mould with tweezers, sprung out to grip the inside of the ring and give about 5 seconds for the ring to warm up before pouring the metal. It can be a bit tedious but I don't make that many compared to the couple of thousand I cast without the ring every year.

[w30wcf]

45 2.1,
Thank you for your input. Yes, I have read Harvey Donaldson and have heard about the graphite wads that were used by some shooters back then.
I would agree that slower powders would give better results in most situations with plain based bullets when trying to push the envelope.
Glad to hear that you are getting good results with your freechecked 311241's.

I have done some further testing with the polyethylene wads on plain based bullets vs. upside down gas checks and the wads gave superior accuracy even with loads in the 35,000 psi range. It appears to give a better gas seal since it is more elastic. Pressure on the base of the wad compresses it, pushing it outward to give a superior seal against the bore. I'll report more on that in a separate thread .... "plain based bullets at 3,000+f.p.s."

Others-
Thank you for your input and insight as well.

Actually, "sealing the base of the bullet" may not be quite correct.
Perhaps it should be "sealing the bore behind the bullet" or "firewalling the bullet" since most of the base could be exposed as in the Wilke check but not the edge of the rear driving band.

w30wcf

[45 2.1]

I'll report more on that in a separate thread .... "plain based bullets at 3,000+f.p.s."
Actually, "sealing the base of the bullet" may not be quite correct.
Perhaps it should be "sealing the bore behind the bullet" or "firewalling the bullet" since most of the base could be exposed as in the Wilke check but not the edge of the rear driving band.
w30wcf

Glad to see someone else doing this also. You are correct in your last two descriptions, because that is what your doing. You have a PM.

[44man]

I replyed to this and for some reason it didn't get posted. I'll try again if I can remember what I said.
I made a punch to punch out the center of gas checks. I inserted this in the mould at the front drive band of a plain base boolit. The lead flows through it and makes nice boolits. I shot these as fast as a GC boolit with great accuracy. Shooting the same boolit with the same load without the foreward GC showed poor groups. Recovered boolits showed wide, smeared rifling marks but no gas cutting.
We shoot BPCR and only use a piece of paper or nothing at all over the powder and get better accuracy then with plastic or fiber wads.
I have to question the theory that the base must be protected. If the boolit is the correct diameter for the throat and bore, it will upset and seal without gas cutting or damage to the base. Undersized boolits will be gas cut and will benefit from a wad. Another problem with undersized boolits is that they slump more to fill the bore which shortens them and nothing says they will slump straight.
Since lead will shear when pushed too fast, adding a hard drive band or gas check will allow more velocity. BUT THE BOOLIT HAS TO BE THE RIGHT SIZE. Adding a gas check to an undersized boolit is no advantage because it has to be seated in the size die and is the same diameter as the bullet. This harder base can not upset to seal the bore and gas cutting can be worse then on a plain base. It will not be seen at the base but it ruins the boolit higher up and is wiped away by the rifling marks. This can cause a lot of leading even with the GC.
The GC does a very good job of preventing a boolit from skidding and stripping the rifling. I believe that stripping is the worst problem in shooting plain base boolits. Even a poly wad can help because it can grip the base hard enough to allow better spin. But it is not as good as a GC or hard drive band.
Of the hundreds of boolits I recovered, the only ones that showed base damage and gas cutting were the ones that did not fit the throats or bores. A good fitting boolit shows no base damage and doesn't even look like it was fired. A little dirty maybe.
A wad will help seal the bore with undersized boolits but then again, nothing says it will enter the bore straight.

[wmitty]

w30wcf ; could you describe your method of constructing and using the polyethlene base wads you mentioned in your comments concerning the sealing of the barrel wall and bullet's base? I have reversed gas checks using the plain base Lyman 457124 in a Marlin .45-70 and this greatly improved accuracy at the velocity I was trying to achieve. I'd be very interested in learning a new (to me) method of obtaining this seal other than by using a gas check. Thanks!

[Bret4207]

There was an article in on eof the Handloader Cast Bullet Annuals about doing the same thing 44Man talks about. Apparantly a GC will work darn near anywhere, it's just easier to do it on the base.

[StarMetal]

I replied to this also and it disappeared. I was telling w30wcf that a while back we had a 200,000 rpm contest offered by Dan of Mountain Moulds. The rules were anyone that could get a bullet to do 200,000 rpm's and shoot 3 five shot groups one inch or under at 100 yards without cleaning between the groups would get a free mould of their choice from him. No 22 caliber rifles. Well not alot of guys participated or at least didn't post that they did but I got damn close with of all guns a Sako Mannlicher carbine with an 18 1/2 inch barrel with a mini Burris 3x9 scope in 7mm-08 caliber. Hardly a target rig or scope. I mentioned this because I got that Sako to shoot the Lee 130 gr bullet at near 2700 fps and would get a one inch group going and blow it with the fifth shot or one of the other shots. It was the rifle and scope and me the blame. Anyways I used double gaschecks The free gascheck (the one not on the bullet) was sized and then placed in the case mouth inverted and then the gascheck bullet seated overtop it. Being that bullet base didn't come close to the shoulder/neck junction I had no worry about the free check dropping into the powder space. No leading whatsoever. I tried the polyethylene wad and it was worse.

This polyethylene wad is nothing new. Guns & Ammo had an article on it back in the 70's I believe, but for revolver cartridges. I tried them in 45 LC and didn't see too much an improvement. I also tried them recently with rifle bullets that were of the gascheck style, but without the check. I substituted the poly wad. No good results.

To cut the wads you just either get a punch the appropiate size or use an old casing with the mouth edge sharpened little. I sharpen the mouth with the bevel on the inside of the case so it will cut a slightly bigger wad then the caliber. Also the wad should be loaded against the bullet base, that is put the wad in the mouth of the powder charged case then seat your bullet. NEVER push the wad down atop the powder and leave an air space between it and the bullet.

Joe

[andrew375]

andrew,
Let's attack the velocity statement first. First any plastic, metal, whatever cup behind a bullet helps seal the gases better then if nothing was there and that means better performance, thus more velocity. Second adding any weight without changing the powder load increases pressure, thus increases velocity.

I’ve never seen any evidence that gas checks do indeed aid in sealing off the propellant gasses. I don’t see why a .377” dia bullet would not give a perfect seal in a .376” barrel. Also, the bullet itself is subject to plastic and elastic deformation under the pressures exerted by the propellant gasses and in reaction to rapid acceleration, which is how conical bullets work in muzzle loading rifles. It has been shown, by Dave Scoville and others, that best performance is achieved when alloy hardness is matched to peak chamber pressure; that is the alloy is soft enough to upset to seal the throat and bore and yet strong enough to resist shearing forces applied by the rifling. Scoville demonstrated that too hard an alloy caused lead fouling to start at the breach end of the barrel due to the bullet not upsetting and too soft an alloy resulted in lead fouling at the muzzle, resulting from a gap between the trailing edge of the rifling land and the edge of its mating groove as a result of radial shear.

I don’t see how adding weight to the projectile can increase velocity simply because of the increase in pressure; for instance when I use the same load for 250 and 330 gr. bullets in my .44 magnums the 330s are always considerably slower. However, the kinetic energy is more or less identical, which is to be expected otherwise we would find ourselves arguing with the long established laws of thermodynamics, in lay persons terms you don’t get something for nothing! Another example is my .223. A load with the 75g. A-max gives 100 fps more with the 69g.MK and nearly a 400fps more with a 50g jacketed flat base.



Now apparently you haven't dug a lot of bullets out of the your backstop whatever that may be. Yes gaschecks do keep the base of the bullet square, they also keep the gas from cutting up the past the sides of the bullet. I've see gas cutting and I've seen bases deformed by gas pressure and gas heat. Gaschecks do add some mechanical strenght to the alloy bullet to resist stripping in the rifling also. I can't understand how Wilkes gascheck company can't understand the mechanics of gaschecks. Why do they think they are called gaschecks for? If they were thought of as you think of them they would be called bullet strengtheners or base squarers , or something like that.
Joe

Actually I’ve dug many bullets out of backstops, mostly mine, over the years as it is my chief source of alloy. On the occasions where I have witnessed signed of gas erosion on the bullet sides it has invariably been with commercially cast pistol bullets that are typically cast from an alloy akin to a type metal and so are far too hard for their intended application. I have never seen any evidence of the gas check aiding in gripping the rifling; as the gas check is the last part of the bullet to enter the rifling the bullet has to have started rotating the follow the lands well before the gas check can make a difference. I have measured (under a 20x microscope here at work) various of my bullets and the grooves pressed into the bullet by the rifling lands are symmetrical, of even width and show no sign of shear. These include bullets fired at over 600 yards so even though they started out at top velocity they hit the backstop with barely enough energy to penetrate the surface so they were almost perfect specimens for examination.

The Wilke gas check is not a commercial venture but a product of the lade Ed. Wilke who was exploring whether it was necessary for a gas check to completely cover the bullet base; if not then he would try to sell his idea to Hornady as it would save considerable material. In short, Mr. Wilke found that his idea was sound and submitted a set of tools for punching the centres out of gas checks for evaluation by the staff at Handloader magazine. Their testing revealed no degradation in performance and they also explored the application of the gas check by actually casting it in place, firstly as a way to add a gas check to a plain base design and then further up the bullet as a was of increasing the shear strength to take the radial forces exerted by the rifling.

Gas checks got their name, I presume, because they evolved as an answer to a problem which was perceived as being caused by inadequate gas sealing. Other answers were hollow bases, wads, washers and cladding the bullet in a copper alloy. This was at a time when the technical knowledge, measuring and analytical equipment that we take for granted were largely unknown. Other uninformed knowledge from this era that still keeps cropping up are; “you need to keep stirring a molten alloy to keep it mixed” and “leading is caused by the base of the bullet melting”. The fact that gas checks make a significant contribution to being able to drive cast bullets at high speeds is not questioned, but exactly how they work has proved a far more complex issue.

[44man]

Andrew, very good. There is only one point that will never be quite answered and that is if the gas check aids in taking the rifling. I believe it does because when I pushed the velocity too high, recovered boolits would show some skidding evident at the front drive band caused by entering the rifling too fast and not starting to revolve but the rifling marks on the gas check were perfect. So I presumed the boolit did start out with a skid but when the gas check entered, it took over. Accuracy from this condition never degraded as much as a plain base boolit did. When I installed a GC on the front drive band in the mould, this condition did not exist.
Years ago I had a TC contender in 30-30 and shot the 308-165-SIL GC boolit. It was accurate enough to hit nickels at 100 yd's. However when I tried them without the gas check, every single boolit would go through the paper sideways at 50 yd's. Now I can't believe that the boolit lost enough drive area to destabilize it. The only answer was that the boolits were stripping the rifling. These boolits were cast HARD. They were hard enough to completely penetrate a 13" oak log at 100 yd's after going through a nickel. I could not recover any because there was no berm behind the targets.
In my opinion the name should be changed from gas check to drive band.
Now, would adding another check to another drive band allow condom bullet performance? I don't know because I sold my rifles and only hunt with handguns now. I have nothing to shoot a boolit fast enough to test it. It would be an interesting test.
You are also correct that adding boolit weight will ALWAYS reduce the velocity even while raising pressure. Pressure is the reason heavy boolit charges must be reduced. Of couse there are some that will keep the same charge and even add more powder to show the heavy boolit does go faster.

[felix]

Only if the powder burns better as a result of, does a "slightly" heavier boolit go faster. Not enough faster to talk about, but sometimes the better burn is worth talking about because it usually gives better accuracy. Everybody likes to shoot heavier boolits for this reason. I don't because I can't stand the recoil. I like average weighted boolits. ... felix

[StarMetal]

Andrew,

I meant to say if you don't change the weight of the bullet or it's bearing length, anything that increases the pressure will increase the velocity.

I agree with 44man, I have seen a bullet strip without a gascheck and the not do it with a gascheck.

There's the old trick that if you pass your finger through a candle flame fast you won't get burnt, but if you do it very slow you will. I mention this because the temperature of the gases produced by gunpowder in the chamber is many times over what is needed to totally melt your bullet alloy, BUT the time period that the bullet is exposed to this high heat isn't long enough to melt it. Just like the finger/candle flame thing. What I believe is the gases find flaws or weak areas, if there are any, at the base of the bullet and combined with the pressure and heat "gas cut" through or around those flaw. I have never seen evidence where the base of a bullet has actually been melted. Further more almost all FMJ military rifle bullet do not have the jacket at the base. The lead core is exposed there, but there is never any leading. Yeah I know, it would be so small that the jacket would scrape it out and we wouldn't notice it. That may be the case, but I think otherwise. I think it doesn't get melted. So apparently when a bullet has an unprotected base the gas, the pressure, and the temperature work on it somehow.

Joe

[w30wcf]

I also posted to this yesterday and it disappeared as well.

castalott -
I don't remember that particular statement but I do remember one in one of the very early Cast Bullet newsletters (late 70's) where the reference was something like ..... load a 300 magnum to 40,000 psi and a .30 Carbine to 40,000 psi and the smaller cartridge will give much better accuracy.

StarMetal -
Sorry to hear that the polyethylene wads did not work out as well for you.
I have used them in the .30-30, .44-40 and.45-70 with complete success and have found the best thickness to be .06", and best material to be LDPE (Low density polyethylene). Also, for best results they should be placed with the slightly flared side into the case first.

wmitty-
I use the .06 LDPE sheet from Buffalo Arms http://www.buffaloarms.com/browse.cfm/4,7.htm
I made my own wad punches similar to the drill press type offered by Buffalo arms http://www.buffaloarms.com/browse.cfm/2,242.html
You can purchase .45 Poly Wads also, but they are almost as expensive as gas checks. http://www.buffaloarms.com/browse.cfm/2,247.html
If you send me a PM, I could send 20 or so to you to try out.
Ideally, the wad should be .002-.003" or so over the bullet diameter. Since the wads give the best results with the slightly flared out side loaded into the case first, I draw a line on the sheet using a permanent black marker, then punch through the line. I then push the wad into the case mouth with the line exposed, then seat the bullet.

44man-
Before our replies were lost yesterday, you mentioned that a poly wad would help with an undersized bullet - HOW TRUE! I have an original '73 Winchester that has an oversized .433" groove diameter. I have found that if I load .427" bullets over a .06" thick poly wad they will shoot as well as a .435" bullet. Without the poly wad, accuracy with the .427" bullet is hopeless, with all bullets keyholing. With the wad, the bullet flies true.

The wad seals the gas behind the .006" undersized bullet so the bullet aligns itself in the bore and thus gives accurate shooting. Pressures with the .44-40 loads I am using are 12,000-15,000 psi. which makes a difference as well.

w30wcf

[David R]

In my opinion the name should be changed from gas check to drive band.
Now, would adding another check to another drive band allow condom bullet performance?


Anotheer Spearment? Youbetchya!

David

[45 2.1]

Anotheer Spearment? Youbetchya!

David

Already written up in one of Wolfe's Cast Bullet Annuals.

[Slowpoke]

Already written up in one of Wolfe's Cast Bullet Annuals.

Volume 1 1990 -- page 6

[w30wcf]

andrew375-
Thank you for your input.
"I’ve never seen any evidence that gas checks do indeed aid in sealing off the propellant gasses. I don’t see why a .377” dia bullet would not give a perfect seal in a .376” barrel." They definitely do as pressures increase. And once the pressure has exceeded the strength of the alloy, without a gas check, inaccurate shooting and leading are the result. A copper gas check is many times stronger than bullet alloy and thus has the ability to withstand pressures that bullet alloy can't. THis is certainly more the case with rifle bullets pushed to higher velocities.

"I don’t see how adding weight to the projectile can increase velocity simply because of the increase in pressure;" It depends on the cartridge, and type of powder used. To Felix's and Starmetal's point, here is some data from the Hodgdon manual, 26th edition:
.30-30 / 39 grs. / H414 powder
100 gr. bullet - 2,041 f.p.s. / 23,100 CUP
150 gr. bullet - 2,327 f.p.s. / 38,200 CUP

In my own testing, here is an example where that is also true, but not by much:
Rifle: .30-30 26" barrel
Powder and charge: 4064 - 30 grains Primer: CCI 200
Bullet: 311041 - 173 grs. - 2,046 f.p.s.
Bullet: NEI - 195 grs. - 2,051 f.p.s.

"Gas checks got their name, I presume, because they evolved as an answer to a problem which was perceived as being caused by inadequate gas sealing." In Ideal Manual No. 17 (1906) we first see the term "gas check cup".

Dr. Walter G. Hudson, who was a World Champion Rifle shooter and held many records in his day was working on the problem of trying to achieve 1,500 f.p.s. in the .30-40 with 200+ grain bullets for accurate shooting at 500 yards. The problem he encountered in trying to achieve that goal was fusion, or gas cutting as we know it today.

He tried experimenting with different tin / antimonial alloys for stronger bullets but fusion persisted. He worked with J.H. Barlow of Ideal on bullet design and diameters, even to the point of using a front "gas check" band (front driving band) diameter of .325"(!) but to no avail.

Between the years of 1904 and 1905, Dr. Hudson and Mr. Barlow of Ideal Manufacturing Co. hit upon the idea that a copper alloy spacer to insulate the bullet from the hot powder gases might work. They tried copper discs under plain based bullets, and found that they successfully prevented fusion. Higher velocities were then achieved with no leading. . Further development lead to the cup profile and the first Ideal bullet #308284 (today‘s 311284) developed to use a gas check.

History sure is interesting.
w30wcf

[Bret4207]

There are those who believe a GC is more of a scraper, catching the lead fragments in the groove ahead of the GC and carrying it out the muzzle. I have seen evidence of the GC assisting in taking the rifleing, happens more prequently with lighter bullets pushed fast for me anyway. As to the GC assisting in sealing the bore from the propellant gases, I think it depends on the bore and groove diameter and the GC diameter. If the bore/groove diameter is enough undersize or the GC enough oversize it will assist in the seal. It has to, just as an oversize bullet has to seal if the bore is smooth. It's when we get to the "tip over" point with the pressure that erosion and gas cutting occurs.

Great discussion. Welcome Andrew375.

[44man]

You guys are right about heavy bullets being able to go faster under certain conditions, but what you forget is the wrong powder was used for the light boolit! It was too slow to start with. Granted, it might have been very accurate but we can't talk apples and oranges. Using too slow a powder with light boolits just made the whole process inefficient, sort of like stuffing a .223 with a 40 gr bullet full of 4831. Stepping up to a 70 gr bullet WILL make it go a little faster!
All the illustrations presented here are due to the same process. We must level the playing field and start with the proper powder used with the lighter bullet. Now, adding bullet weight will DECREASE the velocity while INCREASING pressure.
45 2.1, could you possibly scan that article, copy and paste it here? Or is it too big? course you could do installments.

[StarMetal]

I think one thing we may be overlooking on the issue if a gascheck is a scrapper, a gas sealer, or a device to keep the bullet from stripping in the rifling is, that the gascheck is a much harder material then the bullet alloy. What I'm getting at is one poster said that if the bullet fits the throat and isn't undersized that there will be a good seal, which is very true, but perhaps it isn't all about seal with the alloy, it may be pressure of the gas. Maybe there's a point where even if the bullet does seal good that it can't hold up against the gas pressure. This is where a gascheck could and apparently does.

Jacketed bullet seem to shoot ok whether they seal the bore or not, of course if they fit like they are suppose to they are more accurate. What I'm saying is that they don't gascut or fuze.

Joe

[45 2.1]

45 2.1, could you possibly scan that article, copy and paste it here? Or is it too big? course you could do installments.

I haven't seen my annuals for at least 3 years, sorry. Someone else posted the annual and page though.

[Bullshop]

So why can metal case bullets go faster. We always hear its because they are harder, is that it? Does harder seal better and hold the groove better? If you could cast a boolit as hard as a jacket could it go as fast with equal accuracy? Why does a plastic wad let you go faster with a PB boolit when the plastic is softer than the boolit? I just dont get it! I shot some PB boolits at 4300 fps chronoed to a little under 2 MOA which is what the gun was capable of. This was a 55gn 22 from an 30/06. Why would the plastic sabot be able to hold the groove when the harder lead alloy can not? Its all just a fasinating mystery to me.
BIC/BS

[w30wcf]

44man,
Good analogy. It was in answer to the question "I don’t see how adding weight to the projectile can increase velocity simply because of the increase in pressure." In the example given, the pressure increased by the resistance from the heavier bullet driving it faster. To your point, if the question was "If the correct powder is used with a lighter weight bullet, how can adding bullet weight, thereby increasing the pressure make a heavier bullet go faster?" then if the pressure is close to maximum with the lighter weight bullet, it can't.

Tpr. Bret & StarMetal,
I agree totally. Thank you.

Bullshop,
"So why can metal case bullets go faster. We always hear its because they are harder, is that it? Does harder seal better and hold the groove better? If you could cast a boolit as hard as a jacket could it go as fast with equal accuracy?" Yes, yes & yes.

"Why does a plastic wad let you go faster with a PB boolit when the plastic is softer than the boolit?" Think of it as a gasket. All gaskets provide a seal because they are somewhat elastic. When the powder ignites, it puts a lot of pressure against the polyethylene wad, compressing it, making it fit very tightly in the bore behind the bullet, thus sealing it from the hot powder gases.

"Why would the plastic sabot be able to hold the groove when the harder lead alloy can not?" Because it is a hard plastic and is tough enough for its purpose. Not all plastics are the same. A sufficiently hard lead alloy can be pushed to at least 3,500 f.p.s. with accuracy. I've done it in my .22-250.

w30wcf

[felix]

Looks like the subject is well taken care of. It is the most important topic this board has seen in a year, and should be known by all reloaders, cast or otherwise. ... felix

[MTWeatherman]

One more point:

"Why would the plastic sabot be able to hold the groove when the harder lead alloy can not?"

It's the shear strength, not the hardness that is important. Plastic can be made to have a relatively high shear strength...that's why plastic, nylon, etc. is used for gears in many toys, tools, and appliances. Lead wouldn't survive long under the same usage.

Also, it requires much less shear strength to spin a .22 bullet embedded in a sabot than it would a bullet of the same size as the sabot. The weight difference alone would require only about 1/3 the spin energy...but it also requires less energy to spin anything if its weight is closer to the center of rotation (as the .22 bullet is). For equal weight and rotational speed...its much harder to spin a flywheel than a shaft....that's why flywheels are made the way they are (put weight away from the center of rotation)...to store more energy.

[StarMetal]

Bullshop,

Yes I bullet can be cast hard enough to equal a jacket...that would be a zinc bullet. As far as the lead alloys we use, I would think not.

Why does the plastic sabot 22 in your 06 shoot that fast and work when cast don't. I think because the plastic for one creates less friction or resistance to the rifling and two, I think the thermodynamics of plastic can resist or hold up to the few micro seconds of heat from the powder gases and from what friction it has going up the bores. Cast bullets with copper or brass rings cast into them at their groove bands have shown they can be shot much faster then the same bullet without the ring. So, the secret does lie in the bullet alloy somewhere.

Joe

[Suo Gan]

Interesting thread I must say!