Copper or Aluminum

[PopcornSutton]

Which do you prefer? Sage has copper at .017" and aluminum at .015" for 30 caliber. (not gator checks) Does thickness play a roll in your preference?

[Winger Ed.]

What few gas checks I use, I just buy a box of Hornady's.
Until you get up into or past the mid-teens in speed, you can do OK without them.

If I used more, I'd probably make them. For me, I don't use enough to justify getting set up for that.

[gloob]

Copper better. Thicker better.

But your loads might not need better. Then cheaper is better.

But $5/k is barely cheaper. I would only choose aluminum if my bullet shanks are too fat for normal checks to crimp consistently. Or if the price were way more different than $5/k.

[ShooterAZ]

For years and years I have always used the Copper gas checks from Hornady. I bought up a ton of the various checks I needed before all the shortages began to happen. Hopefully I can get by for at least a few more years. If not, I may need to look into a check maker.

[PopcornSutton]

Is there any concern about aluminum in the bore? Aluminum is quite the abrasive. I know there is not much of a bearing surface but it's still there.

[pworley1]

I have used several thousands of both over the years and really can not tell any difference in performance.

[Rapier]

Supposedly the al check has no elasticity and will not grip the base. I just went to double powder coating over 2k fps and changed to all plain base bullets and stopped using GCs entirely.

[tew45]

Never found aluminum to be abrasive. I make my own gas checks from aluminum and they do not seem to be at all abrasive!

[PopcornSutton]

Many abrasives have aluminum in them. Ever see the term "aluminum oxide"? But with a gas check, there is hardly any bearing surface that could cause wear.

As far as the elasticity of aluminum, that may be true. But, copper can be the same way if it is not annealed properly. Several have written they anneal gas checks to make them dead soft, the same reason you anneal case necks so they won't crack or if you are manipulating the case for a wildcat.

[405grain]

I've used both copper and aluminum and I see no difference. On the aluminum gas checks I usually powder coat after crimping the checks on. I don't think about the aluminum checks being abrasive, it's just easier to install the checks before the powder coat. After coating there would be no issue even if the aluminum were abrasive. I haven't seen any problems with either type of gas check.

[elmacgyver0]

I am not going to live long enough to wear out my bore with aluminum gas checks.

[Larry Gibson]

I can and do make my own aluminum [.014/.015 aluminum flashing and .004/.008 pop/beer can/bottle] and brass [.012 or .014] GCs in .22, .30/.31, 8mm, .35 and .45 calibers. I've found they are very adequate for most of my cast bullet shooting. They perform well, perhaps as well, as commercial GCs below 2000 fps. Above 2000 fps they do not perform well. The aluminum .014 GCs I make are most often used for handgun bullets usually upwards of 1200 fps and rifle plinking/casual shooting bullets upwards of 1900 fps. The 45 cal .004/.008 pop/beer can/bottle GCs are for use on PB cast bullets although the .008 GCs seem to work well on GC 45-70 bullets.

I use lubed bullets on which the bullet/GCs will ride a layer of lube in the barrel, thus no worries about any abrasion if there is any.

My preference for best accuracy with rifle bullets is Hornady or, now Lyman, crimp on GCs. I also stockpiled quite a few and have enough for most of my future use. Of my own make my .30 cal brass GCs perform very well up through 2500 fps and give the same accuracy as the Hornady/Lyman crimp ons. The Hornady crimp ons have proven excellent up through 3,000 fps.

Of the other caliber cartridges I shoot cast bullets in I don't really shoot enough cast to make the cost of a GC make worth it. A box of 1K GCs will last a long time with those cartridges. I wouldn't hesitate to use .014/.015 aluminum GCs for those as they all are shot at less than 2000 fps.

[TD1886]

I make my own aluminum gas checks. I tested them along side Hornady checks and the accuracy was the same and often the aluminum beat them. I use different thicknesses of aluminum for different caliber, with the thickness increasing as the caliber gets larger. Unlike Larry my aluminum checks will perform right along Hornadys to even high velocity. I've also recovered many bullets and the checks are still on them. I don't think the aluminum is going to wear the bore any and I believe many come to that conclusion that aluminum oxide is used for an abrasive. When we use aluminum it's shiney and new, plus as Larry mentioned we have lube on our bullets.

[muskeg13]

This will probably raise the hackles on some, but don't leave out zinc. I make my own checks in .22, .264, .30, .32/8mm, .348, .358, .40 and .45 using Freechex and PatMarlin tools. I began using copper sheets PatMarlin sold years ago and aluminum scrap and flashing, but tried zinc roof flashing left over from an anti-moss project with good results. I don't think the check source material matters much for handgun applications or lower velocity rifle loads, but I reserve the copper checks for use in rifle loads approaching or exceeding 2000 fps.

I've never had a problem with loose copper checks, either home-made or store bought, but need to be careful with thickness and shank dimensions with aluminum. My aluminum checks don't form as pretty as the copper ones that look a nice as Hornady or Lyman checks. I lucked out with the zinc flashing being the right thickness, and being rather soft, they fit the shanks well.

[gloob]

Copper, aluminum, and zinc all share a common trait. They're all excellent conductors of heat.

By weight: copper > aluminum > zinc.

By thickness of the check (factoring in the density of each metal): copper > zinc > aluminum.

[Soundguy]

I use mostly copper checks.. but use both copper and aluminum on 45-70 and see 0 difference in them.. the aluminum grip just fine too. As for aluminum being abrasive.. what about the old silver tip ammo.. never heard any warnings about it?

[TD1886]

This will probably raise the hackles on some, but don't leave out zinc. I make my own checks in .22, .264, .30, .32/8mm, .348, .358, .40 and .45 using Freechex and PatMarlin tools. I began using copper sheets PatMarlin sold years ago and aluminum scrap and flashing, but tried zinc roof flashing left over from an anti-moss project with good results. I don't think the check source material matters much for handgun applications or lower velocity rifle loads, but I reserve the copper checks for use in rifle loads approaching or exceeding 2000 fps.

I've never had a problem with loose copper checks, either home-made or store bought, but need to be careful with thickness and shank dimensions with aluminum. My aluminum checks don't form as pretty as the copper ones that look a nice as Hornady or Lyman checks. I lucked out with the zinc flashing being the right thickness, and being rather soft, they fit the shanks well.

Let me say this first: Zinc is a lustrous bluish-white metal. It is found in group IIb of the periodic table. It is brittle and crystalline at ordinary temperatures, but it becomes ductile and malleable when heated between 110°C and 150°C.

Are you sure that zinc flashing is pure zinc? I'm not condoning you using it, just that it doesn't act like pure zinc when you can form it into gas checks. Am I missing something?

[PopcornSutton]

As for aluminum being abrasive.. what about the old silver tip ammo.. never heard any warnings about it?

From Winchester website: The tip of the bullet is not made of real silver, or even real metal for that matter. Rather it is a polymer silver-colored tip. The reason for the use of polymer is to resist deformation

[Soundguy]

I didn't say ballistic silver tip..the new stuff they sold..but the old semi original..ie.. Aluminum jacketed stuff..which later became nickel plated copper. Ps..the aluminum was circa 1974.

The new polymer tipped one's are just nosler's. And nothing like the original.
Previous to 74 the silver jacket was an alloy of copper, nickel and zinc. At one point some were tin plated too.

[megasupermagnum]

I would have zero concern about aluminum as far as bore wear, it's not going to hurt a thing.

My opinion on gas checks is the biggest cost is time. You easily double or triple the time it takes to size bullets with gas checks vs plain base. That's if things are perfectly sized. If you have bigger shanks, or your powder coating is a little too thick, then that takes time to figure out too. With that kind of time invested, does $23 vs $28 per 1000 really matter? Is anyone shooting multiple thousand gas checked bullets a month?

Copper is a superior material for a gas check plain and simple. Aluminum must work fine for some people, but if you are pushing the limits, you are just shorting yourself if you aren't using copper. I only use copper myself, and I also anneal my gas checks. It makes a big difference on a variety of bullets when you aren't fighting springback.

[Soundguy]

My opinion on aluminum for gas checks is that they are best for playing base bullets and if your bullet actually has a gas check shank probably copper is ideal.

[Soundguy]

Another reason why I think aluminum would be fine as a jacket material is remember some bullets use mild steel as a jacket.

[muskeg13]

Let me say this first: Zinc is a lustrous bluish-white metal. It is found in group IIb of the periodic table. It is brittle and crystalline at ordinary temperatures, but it becomes ductile and malleable when heated between 110°C and 150°C.

Are you sure that zinc flashing is pure zinc? I'm not condoning you using it, just that it doesn't act like pure zinc when you can form it into gas checks. Am I missing something?

Yes, I guess you are missing something. This product is 99% zinc and is very ductile and malleable at normal interior and exterior temperatures. It handles just like aluminum flashing and is promoted to kill and prevent moss growth on roofs. It works great for that use as well as for making gas checks.312912

[TD1886]

Yes, I guess you are missing something. This product is 99% zinc and is very ductile and malleable at normal interior and exterior temperatures. It handles just like aluminum flashing and is promoted to kill and prevent moss growth on roofs. It works great for that use as well as for making gas checks.312912

Thanks for that reply. I've not seen the stuff and would like to get my hands on some. Normally zinc is very brittle, thinks the old carbs that were made from it and matchbox cars. Very hard stuff. I thought what you got was zinc coated not pure all the way through.

[TD1886]

I would have zero concern about aluminum as far as bore wear, it's not going to hurt a thing.

My opinion on gas checks is the biggest cost is time. You easily double or triple the time it takes to size bullets with gas checks vs plain base. That's if things are perfectly sized. If you have bigger shanks, or your powder coating is a little too thick, then that takes time to figure out too. With that kind of time invested, does $23 vs $28 per 1000 really matter? Is anyone shooting multiple thousand gas checked bullets a month?

Copper is a superior material for a gas check plain and simple. Aluminum must work fine for some people, but if you are pushing the limits, you are just shorting yourself if you aren't using copper. I only use copper myself, and I also anneal my gas checks. It makes a big difference on a variety of bullets when you aren't fighting springback.

I can assure you I'm not shorting myself on my velocity limits using aluminum gas check.

[muskeg13]

Maybe it's annealed in the manufacturing process to maintain it's softness? I think the exterior coating some thick coated galvanized steel also seems soft. I believe that process calls for steel to be dipped in molten zinc.

Anyway, the zinc washer bullet bases of the '50s that were the forerunners of modern gas checks had to be soft but tough enough to protect rifle and pistol bores.

[TD1886]

Maybe it's annealed in the manufacturing process to maintain it's softness? I think the exterior coating some thick coated galvanized steel also seems soft. I believe that process calls for steel to be dipped in molten zinc.

Anyway, the zinc washer bullet bases of the '50s that were the forerunners of modern gas checks had to be soft but tough enough to protect rifle and pistol bores.

I worked at a USS Steel mill in the galvanizing department. The steel sheet to be galvanized goes through some processes before being zinc coated. The last one right before the zinc it through a furnace and then , like you said, dipped in a pool of molten zinc.

[Larry Gibson]

Maybe it's annealed in the manufacturing process to maintain it's softness? I think the exterior coating some thick coated galvanized steel also seems soft. I believe that process calls for steel to be dipped in molten zinc.

Anyway, the zinc washer bullet bases of the '50s that were the forerunners of modern gas checks had to be soft but tough enough to protect rifle and pistol bores.

"Modern" copper GCs were in use a long time before the '50s. It was the lubes of the time that were the real culprits causing leading. With the advent of "modern" lubes such as the NRA 50/50 formula that negated any advantage the zinc washers provided to prevent leading.

[TD1886]

Here's a good read when copper gas checks were first used:

https://castboolits.gunloads.com/archive/index.php/t-2347.html

[Rich/WIS]

Have used both and only issue with Al was many did not stay on the bullet, would find 10-20% on the ground 25-75 feet in front of the rifle. Whether this was the difference in thickness of the Al, GC shank diameter, or other factor I don't know. Copper checks, either Hornady or Gator checks, did not leave a trail of checks to the target. Crimp-on type checks stayed on, but the Lyman checks did sometimes come off and would be found on the ground, but very very few. Again whether this was the fault of the check or caused by the GC shank size I have no idea. Given the cost difference I use crimp on types and before the panic started had purchased enough to last til my shooting days are done.

[HumptyDumpty]

Thanks for that reply. I've not seen the stuff and would like to get my hands on some. Normally zinc is very brittle, thinks the old carbs that were made from it and matchbox cars. Very hard stuff. I thought what you got was zinc coated not pure all the way through.
A friend told me once, that it is dangerous to weld or cut galvanized steel, because of zinc (oxide?) gas in the former case, and dust in the later. Supposedly very toxic. Could that be an issue with using a zinc gas-check?

[megasupermagnum]

A friend told me once, that it is dangerous to weld or cut galvanized steel, because of zinc (oxide?) gas in the former case, and dust in the later. Supposedly very toxic. Could that be an issue with using a zinc gas-check?

Very toxic might be too strong a term. Harmful is probably a better way to put it. The chances of getting seriously sick or dying from welding galvanized steel are almost nil. Apparently if you breath enough of the fumes you get flu like symptoms. I suppose if you did it daily for years on end you are probably going to end up with health problems, same as running too light a shade will burn our your eyes. Basically all you need to be safe welding galvanized is to have good ventilation. Stick welding is a very good choice, and blow a fan while you do it.

Long story short, no, zinc gas checks are not a health concern.

[HumptyDumpty]

Very toxic might be too strong a term. Harmful is probably a better way to put it. The chances of getting seriously sick or dying from welding galvanized steel are almost nil. Apparently if you breath enough of the fumes you get flu like symptoms. I suppose if you did it daily for years on end you are probably going to end up with health problems, same as running too light a shade will burn our your eyes. Basically all you need to be safe welding galvanized is to have good ventilation. Stick welding is a very good choice, and blow a fan while you do it.

Long story short, no, zinc gas checks are not a health concern.

Well that's a relief to hear; I had unknowingly used some scrap galvanized pipe to practice with my Harbor-Freight welder (I had zero experience or knowledge), and he assured me that I had certainly caused myself harm. Seemed to think that I would eventually develop neurological problems from it.

[Soundguy]

Yeah you would have known it if you would have been affected by welding the galvanized most people just burn it off with a torch or if stick welding use a little bit of a fan or you just don't breathe the fumes I know a guy that got sick from welding galvanized and they just told him to go home and drink a lot of milk he was good the next day

[ChristopherO]

Father in law had a man come to his farm to weld galvanized metal in a confined space that got sick, went home and died. My Dad was a journeyman welder. I was very cautious with galvanized metal.

Zink Gas Checks. Can't see that being a problem.

[hpbear101]

I prefer Sages gas checks, great quality and much cheaper than "name brand." I've used bot aluminum and copper and really never noticed aby difference.

[gloob]

"I've used both aluminum and copper and really never noticed any difference."
- say a lot of shooters

A lot of calibers, there probably isn't any functional difference when using common powders and loads. Some cartridges might just be slightly over the edge where you have to use a check, at all. You don't need much check to reach full power in cartridges that are rated at less than say 35k psi to begin with.

Some calibers might have a variety of cartridges in that caliber, and the full thickness copper check might only be needed for max cast velocity in the higher pressure of those cartridges.

It's completely unsurprising that a lot of people have found no difference between copper and aluminum. But I'd be surprised if someone with the hobby of pushing boolit velocity to the absolute max wouldn't find a difference in some calibers. Because copper is expensive. Manufacturers save money by making steel and aluminum cases, and those ARE inferior (to us, at least). Why wouldn't they save money by making aluminum gas checks if it never made any difference, at all?

Also, the density difference might affect longrange accuracy or ballistic coefficient in specific bullets.

[Larry Gibson]

"But I'd be surprised if someone with the hobby of pushing boolit velocity to the absolute max wouldn't find a difference in some calibers."

Yes, the difference is there......

[TD1886]

"I've used both aluminum and copper and really never noticed any difference."
- say a lot of shooters

A lot of calibers, there probably isn't any functional difference when using common powders and loads. Some cartridges might just be slightly over the edge where you have to use a check, at all. You don't need much check to reach full power in cartridges that are rated at less than say 35k psi to begin with.

Some calibers might have a variety of cartridges in that caliber, and the full thickness copper check might only be needed for max cast velocity in the higher pressure of those cartridges.

It's completely unsurprising that a lot of people have found no difference between copper and aluminum. But I'd be surprised if someone with the hobby of pushing boolit velocity to the absolute max wouldn't find a difference in some calibers. Because copper is expensive. Manufacturers save money by making steel and aluminum cases, and those ARE inferior (to us, at least). Why wouldn't they save money by making aluminum gas checks if it never made any difference, at all?

Also, the density difference might affect longrange accuracy or ballistic coefficient in specific bullets.

Think of the gas check as a gasket. Even a paper gasket, when supported, is very strong. A gas check is supported by the base of the bullet. There's not going to be very much difference between if the check is aluminum or copper. How about the people that anneal their copper checks, wouldn't that make them more weak? If this doesn't convince you how about paper patched bullets? Those can be shot to very high pressures and velocities and survive........ with accuracy I might add.

[gloob]

Think of the gas check as a gasket. Even a paper gasket, when supported, is very strong. A gas check is supported by the base of the bullet. There's not going to be very much difference between if the check is aluminum or copper. How about the people that anneal their copper checks, wouldn't that make them more weak? If this doesn't convince you how about paper patched bullets? Those can be shot to very high pressures and velocities and survive........ with accuracy I might add.

Why do you think there are different gas check thicknesses from 10 thous thick up to 20 thous thick?

[TD1886]

Why do you think there are different gas check thicknesses from 10 thous thick up to 20 thous thick?

I do not think that. What I meant to say is on the smaller caliber like .224 and .243 I use the aluminum flashing as it's thick enough for the gas check shanks that are on bullet which is determined by the mould. On the larger calibers the flashing is too thin and after you applied it, it's not the full diameter you size too. I don't believe in doubling up on the flashing. So I obtain thicker aluminum material for those larger calibers. I hope that I have explained it. Look at all the brands of moulds that are out there. I don't think there is a standard for what thickness gas check they use.

[gloob]

If a 0.010" copper check works for 223, do you think it would work for all calibers, if the shank were sized correctly?

If it was just about the "hardness" as a gasket material, then why are there at least 4 different thickness of copper checks for different caliber bullets? 0.010", 0.014", 0.017", 0.020".

[TD1886]

If a 0.010" copper check works for 223, do you think it would work for all calibers, if the shank were sized correctly?

If it was just about the "hardness" as a gasket material, then why are there at least 4 different thickness of copper checks for different caliber bullets? 0.010", 0.014", 0.017", 0.020".

I can't answer your question I'm not the engineer/engineers that designed them. As I said though as caliber goes up, to a certain degree, I use the thicker aluminum. You realize that a larger caliber doesn't necessarily have more pressure. It may be the larger calibers have more base area then the smaller ones. One thing I never do it anneal my gas check either copper or aluminum. Would you think that them being softer would let the pressure distort the base of the bullet more?

[megasupermagnum]

The various thickness options have nothing to do with their performance. They offer those thicknesses completely for fit options. A good example is 30 caliber rifle, and 32 caliber handguns. Both use a .284" shank, but one is typically sized about .310" or .311", and the other is sized .313" or .314". You can definitely use .017" thick checks on both, but you are deforming the 30 calibers more since you are squeezing that shank down an extra .004" verses if you were using .015" checks. You can sometimes get away with .015" checks on 32 handguns, but sometimes you get a loose fit, thus it's recommended to use .017" thick checks. I've never seen .020" thick checks, but I suspect they would be good for oddball sizes and calibers. An example might be the 9.3mm calibers, which I assume use the same shank as a 35/38 caliber. The thin checks are almost exclusively for plain base bullets, which you want the thinnest possible since you are going to be deforming that bullet a ton no matter what. I'm assuming much under .010" aluminum and they probably don't form very well.

[gloob]

Sage's or Gator offer different nonstandard thicknesses, and these can come in handy if and when your bullet mold is off.

But bullets have a standard thickness of gas check and shank. There's a sticky at the top of the forum, if you want to check it out.

The thickness of the check affects how much heat can be redistributed and absorbed. Barrels aren't perfect. If and when a leak forms on the bullet that allows gas to jet by, that spot will get real hot, real fast. A gas check will absorb and spread that heat around the entire base of the bullet. There needs to be enough material in the check to do that. Aluminum is less than half the density of copper, so for any given thickness of check, it has much less ability to redistribute and absorb heat!

If all you needed was a check thick enough to not get cut through by the rifling, then all checks could be made 6 thousandths thick.

Paper patching and PC work a little differently from checks. PC and paper are both insulators that cover the entire bearing surface. If you put PC or a paper patch only on the base of a bullet and 1/8" up the side, I bet that wouldn't work very well. Any gas jet that formed, the paper/PC would not absorb/redistribute any heat. The bullet would get ruined.

[megasupermagnum]

Sage's or Gator offer different nonstandard thicknesses, and these can come in handy if and when your bullet mold is off.

But bullets have a standard thickness of gas check and shank. There's a sticky at the top of the forum, if you want to check it out.

The thickness of the check affects how much heat can be redistributed and absorbed. Barrels aren't perfect. If and when a leak forms on the bullet that allows gas to jet by, that spot will get real hot, real fast. A gas check will absorb and spread that heat around the entire base of the bullet. There needs to be enough material in the check to do that. Aluminum is less than half the density of copper, so for any given thickness of check, it has much less ability to redistribute and absorb heat!

If all you needed was a check thick enough to not get cut through by the rifling, then all checks could be made 6 thousandths thick.

Paper patching and PC work a little differently from checks. PC and paper are both insulators that cover the entire bearing surface. If you put PC or a paper patch only on the base of a bullet and 1/8" up the side, I bet that wouldn't work very well. Any gas jet that formed, the paper/PC would not absorb/redistribute any heat. The bullet would get ruined.

That's the first time I've ever heard that theory. I'm not necessarily doubting it, I also don't think that's the reason we use the thicknesses we do. To use your example of a .006" thick gas check, someone would likely have to make a custom die to form that, and even then I'm not sure how well it would work. Copper that thin is more like paper than metal. In my research on gas checks, there are multiple theories on what exact functions they provide, but none of the more well known ones involve heat. I'm sure there's a point where a check would be cut or destroyed by rifling, but beyond that the main purposes revolve around providing a better seal against pressure, providing a more positive engagement of the rifling, and maintaining that grip right at the muzzle where it matters.

[gloob]

That's the first time I've ever heard that theory. I'm not necessarily doubting it, I also don't think that's the reason we use the thicknesses we do. To use your example of a .006" thick gas check, someone would likely have to make a custom die to form that, and even then I'm not sure how well it would work. Copper that thin is more like paper than metal.

Lots of casters make plain base gas checks out of soda cans that are less than 4 thousandths thick aluminum. That's all it takes for that particular boolit to no longer foul and tumble in that particular load and gun. Yes, they're pretty flimsy and maybe not great for a commercial product. So let's forget the "paper thin stuff" and go on to factory checks. In 223, a factory check is only 10 thousandths thick.


the main purposes revolve around providing a better seal against pressure, providing a more positive engagement of the rifling, and maintaining that grip right at the muzzle where it matters.

If 10 thousandths copper check works in 223 to do these things, why do they make 30 caliber checks 17 thousandths thick? Why wouldn't they just make all checks 10 thousandths thick, if it made no difference? 10 thousandth thick checks are plenty thick enough to survive shipping and handling and applying, even up to 45 caliber.

Some people think that plain base checks could make regular checks and gas check-shanked bullet molds obsolete. Just put a 4 thousandths thick aluminum check on a 308 boolit, and sky's the limit. I think if they try it, first, they might be disappointed.

[gloob]

We can make boolits really, really hard. Hard enough to grip the rifling. We can alloy small amounts of copper in them to make them stupid hard.

The problem is that the boolit has a pretty low melting point. The other problem is the boolit alloy is really bad at conducting heat. That means the bullet not only melts at a low temperature, it is also easy to melt the surface of the bullet before the center even gets warm.

I don't think it's a coincidence that copper, aluminum, and zinc (zinc washers were a thing, in the past) all have very high thermal conductivity and higher melting temp than lead.

[TD1886]

Lots of casters make plain base gas checks out of soda cans that are less than 4 thousandths thick aluminum. That's all it takes for that particular boolit to no longer foul and tumble in that particular load and gun. Yes, they're pretty flimsy and maybe not great for a commercial product. So let's forget the "paper thin stuff" and go on to factory checks. In 223, a factory check is only 10 thousandths thick.



If 10 thousandths copper check works in 223 to do these things, why do they make 30 caliber checks 17 thousandths thick? Why wouldn't they just make all checks 10 thousandths thick, if it made no difference? 10 thousandth thick checks are plenty thick enough to survive shipping and handling and applying, even up to 45 caliber.

Some people think that plain base checks could make regular checks and gas check-shanked bullet molds obsolete. Just put a 4 thousandths thick aluminum check on a 308 boolit, and sky's the limit. I think if they try it, first, they might be disappointed.

I believe I mentioned this before. I think they make checks from thinner material for the smaller calibers such as .224 because they don't have as a thick recenss where the check goes on the base shank as larger calibers. Let's say your cast bullet is .224 for an example. If they used the thicker 17 thousandsths check for them the shank would have to be 14 thousandths smaller in diameter and that will leave too small of a shank. I would like to believe that the mould designers are the ones that determine what thickness of a gas check will fit the bullet. Am I making any sense?

BTW "free checked bullets" are good up to the very low 2000 fps bracket. I don't free check plain base cast rifle bullets, but do a lot of pistol revolver ones. Not too much of an inconvienance as you apply them when lubing/sizing. That is if you use that lubing/sizing method.

[Willie T]

The smaller the circle, the greater the strength, and ability to withstand more pressure. As an example: If you load your own shot shells, as the bore gets smaller with the sub gauges, SAAMI pressure specs are higher. That is due to the incremental gains in strength as the diameter of the barrel decreases. The .223 diameter is less than 1/2 the diameter of a .45. That smaller diameter makes the cylindrical portion of the check structurally stronger. Thus able to withstand more pressure and hold its shape in the grooves. That increased structural strength at smaller diameter with the same thickness also does not bend as readily to seal the corners in the grooves as easily. Hence a thinner check works better in small calibers.
As for aluminum and copper checks. I have made aluminum and I buy Hornady copper. I don’t load super fast. A little over 2,300 fps in 30-30 and a 357 carbine are the fastest I load cast for. Both homemade aluminum and copper Hornady have worked equally well for me to eliminate leading. I have not been able to match the accuracy I achieve with the copper Hornady checks using my homemade aluminum checks. In the event I can’t get Hornady checks, I can make aluminum. As long as I can buy the Hornady checks for a reasonable price, they are what I use. Learning to make my own checks that match the accuracy I get in my firearms with the copper Hornady checks would reverse that. Self sufficiency is a big part of the reason I cast but I’m addicted to accuracy. I can’t comment with any reasonable insight regarding whether or not the aluminum checks are abrasive to the bore. With that in mind I will refrain from publicly speculating either way.
Willie

[gloob]

Interesting finding regarding accuracy. I suppose accuracy could be affected due to being lighter, which affected the balance of the bullet. Or maybe because the aluminum checks were less symmetrical than factory Hornady checks?

2300 is plenty fast though, I have to say. I think pressure (and time spent at high pressures and potential gas cutting) is the more direct reason for boolit failure than velocity, but you can't get to 2300 fps without high pressures!

I'm not convinced about the smaller diameter strength thing, though. The boolit should provide plenty of strength. Even 4 thous aluminum checks can make the difference in 40+ caliber boolits! (I personally use 10 thous aluminum checks in 10mm, and they not only leave no fouling, they clean out the fouling of previous boolits!) There is also a difference in gas check thickenss between 452 caliber (thinner checks; typically lower pressure pistol cartridges) and 458 caliber (thicker checks; typically higher pressure rifle cartridges).

Surely someone has tried soda can checks in a caliber that should reach 2300 fps with boolits! I would try it if I could. I don't have plain base molds in any caliber that can do that. And my dies won't make soda can checks!

[gloob]

Regarding the "structural strength" thing, I have also recovered checks that fell off the boolit, because they were not seated correctly. The mouth of these checks was barely hanging onto the shank of the boolit. These 10 thous aluminum checks that fell off didn't have any rifling marks on them. Without the bullet shank to provide the strength, I don't think the check has much structural strength to contain pressure.

[Willie T]

As much as I wanted to make my own checks that were the equal of the copper store bought Hornady checks, it was a bitter pill to swallow that I never quite got there.
Willie

[Willie T]

Regarding the "structural strength" thing, I have also recovered checks that fell off the boolit, because they were not seated correctly. The mouth of these checks was barely hanging onto the shank of the boolit. These 10 thous aluminum checks that fell off didn't have any rifling marks on them. Without the bullet shank to provide the strength, I don't think the check has much structural strength to contain pressure.

Agreed. When you get up around 40,000psi, which is in the neighborhood I’m loading to, neither the cast bullet or the gas check is anywhere close to enough to seal and hold by itself.

[Larry Gibson]

Agreed. When you get up around 40,000psi, which is in the neighborhood I’m loading to, neither the cast bullet or the gas check is anywhere close to enough to seal and hold by itself.

I'm loading the 30 XCB bullet to 2900 fps with Hornady GCs to 50,000+ psi w/o any problems of "sealing and holding". However, above 3,000 fps it appears the GCs get hot enough in the 31" barrel that the shanks melt with the GC coming off on muzzle exit.

[gloob]

^Thanks. I had considered requesting specifics from you, in my last post. But I didn't want to impose.

This seems to go along with my thoughts that copper > aluminum for the same reason thicker > thinner. Ability to absorb/redistribute more heat.

By the time Larry's check is hot enough to melt off the shank, copper is such a good conductor of heat, the ENTIRE check has reached the melting temp of the boolit alloy. That's what gives the boolit just enough time to make it out the barrel intact. If it weren't for that check, a spot on the side and bearing surface of the boolit would have been cut and melted long ago. A thinner copper check should have reached the melting point earlier. And if thin enough, one spot on the rim (the worst of the spots that develop a leak) would have gotten way hotter even more prematurely, before that heat could be distributed to the rest of the check. Now that jet of exploding gas (and that point on the base of the boolit) isn't being cooled enough to stop the meltdown. The gas jet will melt the boolit like a torch on wax, the surface melting away, first.

Aluminum isn't as good a thermal conductor as copper, and it's way lighter so there's less of it. It's like using a thinner copper check.

[TD1886]

^Thanks. I had considered requesting specifics from you, in my last post. But I didn't want to impose.

This seems to go along with my thoughts that copper > aluminum for the same reason thicker > thinner. Ability to absorb/redistribute more heat.

By the time Larry's check is hot enough to melt off the shank, copper is such a good conductor of heat, the ENTIRE check has reached the melting temp of the boolit alloy. That's what gives the boolit just enough time to make it out the barrel intact. If it weren't for that check, a spot on the side and bearing surface of the boolit would have been cut and melted long ago. A thinner copper check should have reached the melting point earlier. And if thin enough, one spot on the rim (the worst of the spots that develop a leak) would have gotten way hotter even more prematurely, before that heat could be distributed to the rest of the check. Now that jet of exploding gas (and that point on the base of the boolit) isn't being cooled enough to stop the meltdown. The gas jet will melt the boolit like a torch on wax, the surface melting away, first.

Aluminum isn't as good a thermal conductor as copper, and it's way lighter so there's less of it. It's like using a thinner copper check.

Then why doesn't the paper patch on paper patched bullets just burn up? You know the highest percentage of heat on the bullet is from friction. Sometime look up friction welding on the internet. Want more proof? Have a contest to see who can bolt, pump, lever a fired case out of a rifle the fastest. I bet that case isn't even luke warm. Next take any semi auto and fire the same load and try picking the empty up...even 22 rimfires are real hot. Ever had one go down your shirt? Need more proof....make bow fire starter. There's no flame heat there, it's all 100 percent friction heat.

The bullet along with it check are only in the barrel in the nano seconds. This was talked about when some people say firing a harden lead alloy bullet totally anneals it. Not enough time and there is no evidence of the recovered bullet being as soft as if it were annealed when it hits the target, that is in the dirt, wood, etc.

[gloob]

I'm not sure why paper doesn't burn or at least scorch in a spots along the rifling marks (The rifling lines are where I suspect gas leaks to occur). Either it takes longer for that to happen to paper? Or maybe paper is a better gasket material than copper or aluminum, able to maintain a perfect seal the entire length of the barrel?

The reason that the case isn't as hot coming out of a lever rifle is easy. That's because it's in the relatively cooler chamber for a lot longer than the cases flying out of a semiauto. The heat from the case gets transferred to the chamber for as long as it takes for you to work the lever after firing it, versus the few milliseconds the case stays in the chamber in a semiauto.

I have made the observation that the cases fired out of my Glock come out hotter (read are more painful when they go in my shirt) than the ones out of my FN, and that the FN slide gets noticeably hotter than my Glock after firing a couple mags. And if you examine the point where the case gets extracted, the Glock spits them out after about half the slide travel as the FN. So the case is presumably in the chamber for significantly longer, in the FN. I have also noticed that a batch of hot S&B ammo that caused sticky extraction in my Glock was no problem in the FN, presumably for that reason. You really think the cases get heated up from the friction of extraction after the powder just went off at 2000 degrees and 30k+ psi? One of the problems the military has faced with caseless ammo is that the barrel/chambers overheat much faster, without the case to carry away much of that heat.

Regarding boolits getting annealed, I didn't make that claim, and I agree with you. It doesn't sound very realistic to me. Unless maybe you're trying to shoot boolits in a Whisper at 4000 fps. I read that the bullet manufacturers had to develop a jacketed bullet that didn't explode in a spray of molten lead, immediately after exiting the barrel. But in typical boolits at typical pressures and speeds, the boolit isn't in danger of entirely melting. It has too much mass. The surface of the boolit is a different story, due to the poor thermal conductivity of lead.

[Willie T]

I'm loading the 30 XCB bullet to 2900 fps with Hornady GCs to 50,000+ psi w/o any problems of "sealing and holding". However, above 3,000 fps it appears the GCs get hot enough in the 31" barrel that the shanks melt with the GC coming off on muzzle exit.

Interesting hypothesis on why the jackets shed. Those speeds with cast are uncharted water for me.

[TD1886]

I'm not sure why paper doesn't burn or at least scorch in a spots along the rifling marks (The rifling lines are where I suspect gas leaks to occur). Either it takes longer for that to happen to paper? Or maybe paper is a better gasket material than copper or aluminum, able to maintain a perfect seal the entire length of the barrel?

The reason that the case isn't as hot coming out of a lever rifle is easy. That's because it's in the relatively cooler chamber for a lot longer than the cases flying out of a semiauto. The heat from the case gets transferred to the chamber for as long as it takes for you to work the lever after firing it, versus the few milliseconds the case stays in the chamber in a semiauto.

I have made the observation that the cases fired out of my Glock come out hotter (read are more painful when they go in my shirt) than the ones out of my FN, and that the FN slide gets noticeably hotter than my Glock after firing a couple mags. And if you examine the point where the case gets extracted, the Glock spits them out after about half the slide travel as the FN. So the case is presumably in the chamber for significantly longer, in the FN. I have also noticed that a batch of hot S&B ammo that caused sticky extraction in my Glock was no problem in the FN, presumably for that reason. You really think the cases get heated up from the friction of extraction after the powder just went off at 2000 degrees and 30k+ psi? One of the problems the military has faced with caseless ammo is that the barrel/chambers overheat much faster, without the case to carry away much of that heat.

Regarding boolits getting annealed, I didn't make that claim, and I agree with you. It doesn't sound very realistic to me. Unless maybe you're trying to shoot boolits in a Whisper at 4000 fps. I read that the bullet manufacturers had to develop a jacketed bullet that didn't explode in a spray of molten lead, immediately after exiting the barrel. But in typical boolits at typical pressures and speeds, the boolit isn't in danger of entirely melting. It has too much mass. The surface of the boolit is a different story, due to the poor thermal conductivity of lead.

Do you know how a diesel engine works? Do you know why an air compressor gets hot? You never did mention anything about why a bow/drill can start a fire. To answer your question do I really think an ejected cartridge case main heat source is friction, no, I know it is. Thing is you haven't a clue about any of this and are grasping at straws.

Gloob I'm editing to say I'm finished with this area of discussion, but you may have the last word.

[Larry Gibson]

Then why doesn't the paper patch on paper patched bullets just burn up? You know the highest percentage of heat on the bullet is from friction. Sometime look up friction welding on the internet. Want more proof? Have a contest to see who can bolt, pump, lever a fired case out of a rifle the fastest. I bet that case isn't even luke warm. Next take any semi auto and fire the same load and try picking the empty up...even 22 rimfires are real hot. Ever had one go down your shirt? Need more proof....make bow fire starter. There's no flame heat there, it's all 100 percent friction heat.

The bullet along with it check are only in the barrel in the nano seconds. This was talked about when some people say firing a harden lead alloy bullet totally anneals it. Not enough time and there is no evidence of the recovered bullet being as soft as if it were annealed when it hits the target, that is in the dirt, wood, etc.

It's not really the friction causing the most heat on the GC. It is the pressure. When a metal or anything else is compressed, it creates heat. The greater the compression the greater the heat produced. The pressure creates compression of the GC and the shank. Also, the higher the psi of the load the more heat is generated by the burning gas. Thus at 50,000+ psi it appears there is sufficient pressure on the GC to create sufficient heat. The paper is an excellent insulator and does not convey heat well and probably its compression does not create the same heat. Additionally, since PP'd bullets are not shot at 50,000+ psi successfully we don't really know if the paper is or would be burnt or not.

[TD1886]

It's not really the friction causing the most heat on the GC. It is the pressure. When a metal or anything else is compressed, it creates heat. The greater the compression the greater the heat produced. The pressure creates compression of the GC and the shank. Also, the higher the psi of the load the more heat is generated by the burning gas. Thus at 50,000+ psi it appears there is sufficient pressure on the GC to create sufficient heat. The paper is an excellent insulator and does not convey heat well and probably its compression does not create the same heat. Additionally, since PP'd bullets are not shot at 50,000+ psi successfully we don't really know if the paper is or would be burnt or not.

Yes pressure creates heat. I don't agree with on your assumption. My assumption is it's friction. There is only one way to prove it that I know of and that would be to fire the bullet in an air rifle that would put that much pressure behind the bullet and of course the friction would be present.

Apparently you have forgotten the NRA's paper patch test of the 300 Winchester Magnum using 150, 169, and 180 paper patched bullet and accuracy was 1.47 inches in a 25 mph wind. Actually groups varied as they changed alloy. They did rather good and that shows that paper patch did hold up to the powder heat.

Back to the heat from the powder burn why doesn't Kapok catch fire and also many of us shooter find Dacron tuffs in front of our shooting benches. I don't know about other, but the loads I used those materials in wasn't just lower velocity loads.

[gloob]

^Please be careful, there, Larry. Boyle's Law applies to gases, only. Liquids and solids are incompressible.

The only heat to the check that would be indirectly caused by pressure would be due to mechanical deformation/flow of the copper as the pressure formed it to the bore and base of the bullet, and that wouldn't be significant in this context. And then there is the friction as it goes down the bore.

Indeed maybe friction can cause the surface of a bullet to melt. The total amount of heat created by friction out a 20" barrel is mostly the same no matter how fast you push it. But the faster you push the boolit out, the more chance you can melt an extremely shallow outer layer of boolit before the heat can transfer to the core. Perhaps just a tiny layer of the surface might melt, but enough to allow a leak that will quickly consolidate into one big channel/gas-jet down the side of the bullet. Once this forms, the heat of the burning gases jetting by at 30k psi drops the hammer.

The check maybe continues to seal. But thicker and more copper in the gas check, the more it can provide cooling or heat-sinking to a leak that has already formed despite the check.

So I'm still stuck on gas leak as important to boolit failure for the reason check material and thickness should be important when pushing the limits of pressure and velocity.

[gloob]

I think leaks are just part of shooting boolits fast. A boolit is maybe like a boat that leaks and will eventually sink. The idea is to limit the leaks just long enough to make it through a very short trip. This is why lube grooves need a certain amount of lube in very much excess of what would be deposited into the pores of the barrel, should the lube groove remain sealed. There has to be enough lube to be melted and sprayed into the inevitable leaks, for this short trip.

[TD1886]

^Please be careful, there, Larry. Boyle's Law applies to gases, only. Liquids and solids are incompressible.

The only heat to the check that would be indirectly caused by pressure would be due to mechanical deformation/flow of the copper as the pressure formed it to the bore and base of the bullet, and that wouldn't be significant in this context. And then there is the friction as it goes down the bore.

Indeed maybe friction can cause the surface of a bullet to melt. The total amount of heat created by friction out a 20" barrel is mostly the same no matter how fast you push it. But the faster you push the boolit out, the more chance you can melt an extremely shallow outer layer of boolit before the heat can transfer to the core. Perhaps just a tiny layer of the surface might melt, but enough to allow a leak that will quickly consolidate into one big channel/gas-jet down the side of the bullet. Once this forms, the heat of the burning gases jetting by at 30k psi drops the hammer.

The check maybe continues to seal. But thicker and more copper in the gas check, the more it can provide cooling or heat-sinking to a leak that has already formed despite the check.

So I'm still stuck on gas leak as important to boolit failure for the reason check material and thickness should be important when pushing the limits of pressure and velocity.

Gloob you got me interested again plus some things Larry said. You're right about Boyle's Law. As far as pressure in the bore, after a certain point, it is decreasing as the volume of the bore increases farther along the bullet travels.

Like you I too would be more concerned with gas checks leaking. I really haven't seen real good evidence of this. What does amaze me is that as soft, or maybe better said "less strong" paper is on the base of a paper patched bullet that why the pressure doesn't deform that base? Even on flat base naked bases you don't see the deformation that you would think to be there. Yes , we do see the gas cutting.

Gloob I feel you are too concerned about gas checks conducting heat and not being strong enough for the job. Think of a heat sink. We're all familar with the aluminum heat sinks on electronic equipment. The are rather large compared to what they are cooling. Even the fins on air cooled engines have a lot of area. A gas check doesn't and I don't really think it's getting rid of much heat from the bullet or the powder combustion. Not enough to worry about.

I'm scratching my head thinking about Larry talking about melting the gas check shank and the check coming off. How does he obtain the accuracy he often talks about if that is happening?

[TD1886]

By the way one gram of powder produces about 3700 joules energy from high energy gun powder. There's is only one powder manufacturer that releases this type of data that I know of. You figure out who it is. While you are at figure out what the C or F degree of 3700 Joules is!!

[Larry Gibson]

"I'm scratching my head thinking about Larry talking about melting the gas check shank and the check coming off. How does he obtain the accuracy he often talks about if that is happening?"

I don't obtain nor claim the level of accuracy above 3,000 to 3,100 fps that I get at 2900 fps. That's where the GCs come off. Recovered such GCs show evidence of melted alloy inside the GC cup. Recovered bullets shot at 2900 fps show little sign of gas cutting or gas "leaking". BTW, the level of accuracy at 2900 fps is obtained in my 30x60 XCB rifle. It has a 31" barrel with a 16" twist. You're not going to get the same 1 - 1.5 moa accuracy with a sporter barreled 30-06 with a 10" twist......

gloob

"The only heat to the check that would be indirectly caused by pressure would be due to mechanical deformation/flow of the copper as the pressure formed it to the bore and base of the bullet, and that wouldn't be significant in this context. And then there is the friction as it goes down the bore."

I'm not talking about deformation of the GC. Talking about possible deformation of the much softer bullet GC shank. That's the only part that is melting and then not always with every bullet pushed above 50,000 psi/3000+ fps. If the heat to do that is from friction in the bore then how do you explain no melting of the bullet, no leading and only evidence of melting in recovered GCs is inside the GC?

Here's the recovered 30 XCB shot at 2900 fps with GCs, Not no alloy welded/soldered to the inside of the GCs.

313729

Here's the remains of 2 Hornady GCs recovered from the inside of the Oehler Sky Screens. Note the alloy welded/soldered to the inside of the GCs. Both GCs and the Sky Screen housing were severely damaged......

313730

Whatever we theorize the cause to be, the effect is still the same.

[gloob]

Gloob you got me interested again.
I'm glad I didn't put you off, yet. I know I am annoying, and I'm trying to improve on that.


As far as pressure in the bore, after a certain point, it is decreasing as the volume of the bore increases farther along the bullet travels.
Yep. An air compressor gets hot because it's compressing the air. But when you let the air back out, the air gets colder. It absorbs heat as it decompresses.

In a firearm, the powder releases energy in an exothermic reaction. So despite the pressure reducing back to normal, there is still a lot of heat.


Gloob I feel you are too concerned about gas checks conducting heat and not being strong enough for the job. Think of a heat sink. We're all familar with the aluminum heat sinks on electronic equipment. The are rather large compared to what they are cooling. Even the fins on air cooled engines have a lot of area. A gas check doesn't and I don't really think it's getting rid of much heat from the bullet or the powder combustion. Not enough to worry about.

The heatsink in a computer is dissipating heat by dissipating it to air. It has to take the heat being generated from a small point source and spread that out so that it contacts enough (room temperature) air to keep the cooling at a sufficient rate, continuously, even after it reaches steady state and the heatsink itself is now pretty darn hot. The gas check starts out cold to begin with. It's not going to dissipate that heat to anywhere except itself (except a little to the very surface of the boolit shank), so it doesn't need fins. It only has to absorb and spread out heat from the hot spots at the rim for the fraction of a second before the boolit exits.

It's like a tampon. Once it's saturated, it no longer works. But if it lasts long enough to do the job, that's all you need it to do. To be effective against a stronger, higher pressure leak, you need a bigger tampon.

[TD1886]

Larry

I'm not talking about deformation of the GC. Talking about possible deformation of the much softer bullet GC shank. That's the only part that is melting and then not always with every bullet pushed above 50,000 psi/3000+ fps. If the heat to do that is from friction in the bore then how do you explain no melting of the bullet, no leading and only evidence of melting in recovered GCs is inside the GC?

What you are seeing inside those gas checks tin that is part of the alloy make up of your bullet. Tin melts lower then all the rest of the alloys in mix. Friction from going the bullet going up the bore plus the heat from the powder combustion is what heats both the bullet and bore. I wasn't referring to friction heating the bore and bullet, I was referring to the friction yanking a case out of the chamber in a micr second, one which in many cases is still slightly obturated to the chamber walls.

I didn't think you were getting accuracy with those checks coming off and whatever is happening to the shanks.

Nobody answered why the pressure in the NRA full power loads (one's in the 50k bracket and over) wasn't deforming the base of the bullets when only paper protected them.

[TD1886]

I'm glad I didn't put you off, yet. I know I am annoying, and I'm trying to improve on that.


Yep. An air compressor gets hot because it's compressing the air. But when you let the air back out, the air gets colder. It absorbs heat as it decompresses.

In a firearm, the powder releases energy in an exothermic reaction. So despite the pressure reducing back to normal, there is still a lot of heat.



The heatsink in a computer is dissipating heat by dissipating it to air. It has to take the heat being generated from a small point source and spread that out so that it contacts enough (room temperature) air to keep the cooling at a sufficient rate, even after it reaches steady state and the heatsink itself is now pretty darn hot. The gas check starts out cold to begin with. It's not going to dissipate that heat to anywhere, so it doesn't need fins. It only has to absorb and spread out heat from the hot spots at the rim for the fraction of a second before the boolit exits.

It's like a tampon. Once it's saturated, it no longer works. But if lasts long enough to do the job, that's the goal.

Gloob I believe you meant when you let the air out of an air compressor it "cool"s by expanding. All gases that expand cool and some quite cold! That's the principle of how air conditioners work.

I'm sure the checks get plenty hot, you know thought I've never seen a fired recover check that wasn't still shiney. That is never seen them to have that annealed look and for that matter they were still harder then if they were annealed.

I believe that it is the friction of going through the air that a 220 Swift comes apart from the core melting. It's going about Mach 3.64 and plus you have the heat already in it from friction going down the bore and the powder gases burning.

[gloob]

...What does amaze me is that as soft, or maybe better said "less strong" paper is on the base of a paper patched bullet that why the pressure doesn't deform that base? Even on flat base naked bases you don't see the deformation that you would think to be there...


In this case, the path of least resistance must be the boolit to be accelerated more, rather than the base to deform. But for a relatively thin gas check with air between base of boolit and check, the check will be formed to the base of the bullet.

If the bullet is accelerated out the way, that increases the volume. That's what pressure does, it wants to expand. The only reason for the base of the bullet to be say cratered inward, deforming the entire bullet in order to create a tiny bit more volume, is if the friction was somehow really high between bullet and barrel to the point of an obstruction. And if that was the case, why would it stop there? The center of the bullet would just get blown out, leaving a donut of lead in the barrel. I bet you have a kB before that happens.

This is why a gas check shouldn't need "structural strength" anymore than PC or paper patching does.

[TD1886]

Larry here's a tip for you. Put a paper liner inside your gas check. It will insulate it from the shank. It won't interfere with the check. I've done this. See if this stops that melt inside the gas check.

[Larry Gibson]

Larry here's a tip for you. Put a paper liner inside your gas check. It will insulate it from the shank. It won't interfere with the check. I've done this. See if this stops that melt inside the gas check.

I suppose I could revisit 3000+ fps and try that but to what end other than seeing if it works? I'm quite satisfied with 2900 fps with the 30 XCB. That well proved my point with ternary alloyed, lubed cast bullets regarding the RPM Threshold, that properly designed and lubed cast bullets of the correct alloy do not strip in the rifling or lead the barrel at really high velocity and that 1 - 1 1/2 moa accuracy with 10 shots strings was possible to 600 yards. There isn't exactly a lot of shooters building HV cast bullet rifles so an actual need to find out isn't apparent. Besides, I've got so many other test irons in the fire right now w/o enough time to complete those in a timely manner.

[gloob]

Larry here's a tip for you. Put a paper liner inside your gas check. It will insulate it from the shank. It won't interfere with the check. I've done this. See if this stops that melt inside the gas check.

I predict this will just mean he loses accuracy even earlier or at lower velocity. If the entire check is reaching melting temp by the time the boolit exits, I say it's due to a significant hot spot or leak on the rim of the check and his boolit is already suffered significant gas cutting down the side. I think the boolit would not be accurate by this point, even if you had the paper in there to prevent the check from melting off.

In my prediction, the base of bullet (as a whole, or on average) would stay a bit cooler, overall, due to this paper. But the gas check would get hotter, faster, because it can't share some of the heat with the base of the boolit, anymore. And the gas cutting down the side would be worse, i.e. it would become detrimental to accuracy at a lower velocity/pressure.

If there is no leak at all, the gas check should not get hot enough to melt the boolit. 2900 fps maybe changes that game of course! But we generally see boolit failure from the side. The base of the boolit doesn't melt first. The base is buffered by a boundary layer. Where gas jets by is much closer to max temperature, and all the time. So in my thinking, you could say the gas check is there to protect the side of the bullet by sharing the damage/heat to itself and the rest of the base which doesn't normally fail.

edit: also just realized one potential reason a paper patch doesn't scorch or burn. It might ignite at similar temperature to melting point of boolit alloy, but it has to "cook" a bit before it burns. At that temp, the structures decompose first, before ignition. At high enough temp over ignition temp this might occur "instantly," but the surface of the lead will melt right as it reaches that temp and gets enough additional heat to phase change from solid to liquid, without any waiting. And with enough pressure and gas jet velocity, lead will perhaps get eroded out as it softens even before it reaches melting point.

[TD1886]

I predict this will just mean he loses accuracy even earlier or at lower velocity. If the entire check is reaching melting temp by the time the boolit exits, I say it's due to a significant hot spot or leak on the rim of the check and his boolit is already suffered significant gas cutting down the side. I think the boolit would not be accurate by this point, even if you had the paper in there to prevent the check from melting off.

In my prediction, the base of bullet (as a whole, or on average) would stay a bit cooler, overall, due to this paper. But the gas check would get hotter, faster, because it can't share some of the heat with the base of the boolit, anymore. And the gas cutting down the side would be worse, i.e. it would become detrimental to accuracy at a lower velocity/pressure.

If there is no leak at all, the gas check should not get hot enough to melt the boolit. 2900 fps maybe changes that game of course! But we generally see boolit failure from the side. The base of the boolit doesn't melt first. The base is buffered by a boundary layer. Where gas jets by is much closer to max temperature, and all the time. So in my thinking, you could say the gas check is there to protect the side of the bullet by sharing damage control with the rest of the base.

edit: also just realized one potential reason a paper patch doesn't scorch or burn. It might ignite at similar temperature to melting point of boolit alloy, but it has to "cook" a bit before it burns. At that temp, the structures decompose first, before ignition. At high enough temp over ignition temp this might occur "instantly," but the surface of the lead will melt right as it reaches that temp and gets enough additional heat to phase change from solid to liquid, without any waiting. And with enough pressure and gas jet velocity, lead will perhaps get eroded out as it softens even before it reaches melting point.

Thing is Larry did say that the check itself DID NOT MELT, he believes the bullet shank started to melt because he found some form of alloy inside the gas check. I presume it's the tin. Larry does like some extra tin in his alloy blends. Larry chime in if I'm wrong about that.

[TD1886]

I suppose I could revisit 3000+ fps and try that but to what end other than seeing if it works? I'm quite satisfied with 2900 fps with the 30 XCB. That well proved my point with ternary alloyed, lubed cast bullets regarding the RPM Threshold, that properly designed and lubed cast bullets of the correct alloy do not strip in the rifling or lead the barrel at really high velocity and that 1 - 1 1/2 moa accuracy with 10 shots strings was possible to 600 yards. There isn't exactly a lot of shooters building HV cast bullet rifles so an actual need to find out isn't apparent. Besides, I've got so many other test irons in the fire right now w/o enough time to complete those in a timely manner.

Larry would be interesting to know if you would do the test, but I ask how would you collect the gas check fragments if it doesn't work? BTW did you recover those bullets that all this happened too and if so was the shank indeed melted?

[TD1886]

I suppose I could revisit 3000+ fps and try that but to what end other than seeing if it works? I'm quite satisfied with 2900 fps with the 30 XCB. That well proved my point with ternary alloyed, lubed cast bullets regarding the RPM Threshold, that properly designed and lubed cast bullets of the correct alloy do not strip in the rifling or lead the barrel at really high velocity and that 1 - 1 1/2 moa accuracy with 10 shots strings was possible to 600 yards. There isn't exactly a lot of shooters building HV cast bullet rifles so an actual need to find out isn't apparent. Besides, I've got so many other test irons in the fire right now w/o enough time to complete those in a timely manner.

Larry I was shooting my Yugo 48 B 8mm Mauser, which is scoped, a few years ago. I was shooting the Lyman 323471 moving along at tad over 2000 fps. Certainly no speed demon as you XCB load. I had a Directv satelite dish up at a measure 500 yards. I was shooting at paper target and I had 4 cartridges left so I shot at the dish. This group isn't in MOA it's in actual inches and as you can see for that distance with a military rifle it's not shabby at all.

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[gloob]

Thing is Larry did say that the check itself DID NOT MELT, he believes the bullet shank started to melt because he found some form of alloy inside the gas check. I presume it's the tin. Larry does like some extra tin in his alloy blends. Larry chime in if I'm wrong about that.

Of course it didn't melt. Copper melts at over 1900F. But the cooling effect is dependent on the differential, so when the check gets hotter it doesn't absorb as much heat from the gases. The barrel is cooling this jet of gas on its side. But the check is helping to cool those gases, as well. And when the check gets hot enough to melt the base, that's not good either.

A thicker check could absorb more heat, faster or longer, before it peters out and is "full."

[TD1886]

Of course it didn't melt. Copper melts at over 1900F. But the cooling effect is dependent on the differential, so when the check gets hotter it doesn't absorb as much heat from the gases. The barrel is cooling this jet of gas on its side. But the check is helping to cool those gases, as well. And when the check gets hot enough to melt the base, that's not good either.

A thicker check could absorb more heat, faster or longer, before it peters out and is "full."

Well Gloob I'm waiting on a reply from Larry if the found the bullet that check came off of to see whether the base melted a lot or not. I feel it may be the thin leaching out first as it has the lowest melting point.

I've pushed my 30-06 to limits with a cast 172 grain bullet which was every bit into the 50K bracket and I've never seen anything like that. Only time I've every seen alloy on a gas check is when that gas check pushed some leading out of the bore.

[gloob]

I feel like you still don't get what I'm saying. And I'm fine if you don't agree, but I wish you got it, first.

The base of a boolit doesn't melt (the side does). So the check, which covers the base, should not only not melt, it shouldn't reach the temperature that would even melt lead. The only way it reaches that temp, demonstrated by Larry's boolits, is because it sucked out heat from a jet of gas that would have otherwise contributed to melting the side of the boolit.

[Larry Gibson]

Larry

I didn't think you were getting accuracy with those checks coming off and whatever is happening to the shanks.

Nobody answered why the pressure in the NRA full power loads (one's in the 50k bracket and over) wasn't deforming the base of the bullets when only paper protected them.


Once the velocity went above 3000 fps the GCs started coming off. They do considerable damage to the SkyScreens which I'll post later. As I've stated and posted numerous time the best consistent HV accuracy of 1 - 1.5 moa (10 shot groups) comes just over 2900 fps. At 3100 fps the 10 shot groups opened to 3.75" with every flyer being also a bullet that lost its GC as seen when the SkyScreens were struck by the GC. Also at 3100 fps the bullet out of the 16" twist is at the front edge of the RPM Threshold.

In the NRA Cast Bullets Supplement Col. Harrison notes in the article starting on page 108 the success with the 160 gr PP'd bullet in the 300 WM with the full load gave an average of 2.6 and 2.2 moa (five 5 shot group average). Unfortunately, the pressure and velocities were only estimates. Also he did not recover any bullets or patches so we don't know whether the patch was "burnt" or not of if the base of the bullet was damaged.

[Larry Gibson]

Thing is Larry did say that the check itself DID NOT MELT, he believes the bullet shank started to melt because he found some form of alloy inside the gas check. I presume it's the tin. Larry does like some extra tin in his alloy blends. Larry chime in if I'm wrong about that.

The bullets were cast of Lyman #2 alloy.

[Larry Gibson]

Larry would be interesting to know if you would do the test, but I ask how would you collect the gas check fragments if it doesn't work? BTW did you recover those bullets that all this happened too and if so was the shank indeed melted?

If I did the test I'm not sure how I would collect the shed GCs. The previous shed GCs are very destructive to the SkyScreens. The fragments shown were found inside the SkyScreen housings. Here you can see the damage done not only by the Hornady GCs shed at 3000+ fps but also from aluminum GCs shed at 22-2400+ fps. Frankly, having replaced and/or repaired several of my SkyScreens I'm no all that keen on doing more repair/replacement. I've already learned at what velocities the checks become separated from the bullets.

No, I did not recover any of the bullets that had shed their GCs. When one screen stopped reading [the fragment was laying on the sensor blocking it from reading] and a support arm was shot in two by a GC I said "enough is enough".

Here's just a few pic's of the damaged SkyScreens;

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[Larry Gibson]

Larry I was shooting my Yugo 48 B 8mm Mauser, which is scoped, a few years ago. I was shooting the Lyman 323471 moving along at tad over 2000 fps. Certainly no speed demon as you XCB load. I had a Directv satelite dish up at a measure 500 yards. I was shooting at paper target and I had 4 cartridges left so I shot at the dish. This group isn't in MOA it's in actual inches and as you can see for that distance with a military rifle it's not shabby at all.

313753

The 323471 ia an excellent bullet to use at LR out of good Mauser barrels. The bullet itself has several attributes which make it an excellent choice for pushing the RPM Threshold. Additionally thegroove depth of the military 8mm Mauser is .005" deep as opposed to .003 - .004 for most commercial groove depth. The deeper mauser grooves really grasp the long bearing surface of the Loverin style 323471 bullet. That bullet is my favorite LR bullet for use in my own Yugo M24/47. I push that bullet right at 2000 fps also and it hold very well at 500 - 600 yards as you've demonstrated. Well done.

[Larry Gibson]

Back to the thread topic. Probably 15 - 20 +/- years ago I got a GB Lee 6 cavity C326-190-FN mould. I also had a GC maker. I obtained some .012" brass shim from McMaster-Carr (?) and made some 8mm GCs. I decided to make a comparison of them to the Hornady 8mm GCs. I had a lot of Turk primed cases I was using back then so I cast a bunch of the bullets out of COWW +2% tin, sized them at .325, GC'd some with the Hornady's and some with my own GCs, lubed them with Javelina and loaded them over 4895 + a dacron filler in the Turk cases. I used my Yugo 24/47 w/Leupold 6X scope for the test. I shot the Hornady's first shooting two foulers then 10 shots for group. I then let the barrel cool, cleaned it and repeated the test. There was only .01" difference between the groups and given the Turk cases, only visually sorted bullets and no load work up they were close enough for government work.... I then sized, lubed and GC'd the remaining 600+ bullets with my own GCs and loaded them in the Turk cases I had. I've still a couple hundred left as they have prove to be an excellent "walk about" load for use in my Yugo M48.

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[TD1886]

I feel like you still don't get what I'm saying. And I'm fine if you don't agree, but I wish you got it, first.

The base of a boolit doesn't melt (the side does). So the check, which covers the base, should not only not melt, it shouldn't reach the temperature that would even melt lead. The only way it reaches that temp, demonstrated by Larry's boolits, is because it sucked out heat from a jet of gas that would have otherwise contributed to melting the side of the boolit.

Oh I get what you are saying. Now I'm wondering if that jet of gas got ahead of the check and sprayed it with molten alloy that it gas cut, rather then the base of the bullet melting.

[TD1886]

The 323471 ia an excellent bullet to use at LR out of good Mauser barrels. The bullet itself has several attributes which make it an excellent choice for pushing the RPM Threshold. Additionally thegroove depth of the military 8mm Mauser is .005" deep as opposed to .003 - .004 for most commercial groove depth. The deeper mauser grooves really grasp the long bearing surface of the Loverin style 323471 bullet. That bullet is my favorite LR bullet for use in my own Yugo M24/47. I push that bullet right at 2000 fps also and it hold very well at 500 - 600 yards as you've demonstrated. Well done.

Thank's Larry. That Mauser is exactly as you described and mine was a brand new unissued one. I think the 8x57 Mauser is one of the best cartriges and it certainly has stellar performance with cast bullets.

[TD1886]

Back to the thread topic. Probably 15 - 20 +/- years ago I got a GB Lee 6 cavity C326-190-FN mould. I also had a GC maker. I obtained some .012" brass shim from McMaster-Carr (?) and made some 8mm GCs. I decided to make a comparison of them to the Hornady 8mm GCs. I had a lot of Turk primed cases I was using back then so I cast a bunch of the bullets out of COWW +2% tin, sized them at .325, GC'd some with the Hornady's and some with my own GCs, lubed them with Javelina and loaded them over 4895 + a dacron filler in the Turk cases. I used my Yugo 24/47 w/Leupold 6X scope for the test. I shot the Hornady's first shooting two foulers then 10 shots for group. I then let the barrel cool, cleaned it and repeated the test. There was only .01" difference between the groups and given the Turk cases, only visually sorted bullets and no load work up they were close enough for government work.... I then sized, lubed and GC'd the remaining 600+ bullets with my own GCs and loaded them in the Turk cases I had. I've still a couple hundred left as they have prove to be an excellent "walk about" load for use in my Yugo M48.

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Job well done Larry. I have tested my checks along with Hornady and they are the equal and sometimes beat them, not all the time.

[gloob]

Larry's data is quite convincing. At 3100 fps, the copper checks started falling off and more importantly started throwing fliers. The aluminum checks started doing that at 2400 fps.

Bringing this back to the topic of "copper vs aluminum," I said it in my first post. Copper > aluminum. But sometimes aluminum is good enough for your gun and load. Then there's no difference as far as you're concerned!

[TD1886]

Larry's data is quite convincing. At 3100 fps, the copper checks started falling off and more importantly started throwing fliers. The aluminum checks started doing that at 2400 fps.

Bringing this back to the topic of "copper vs aluminum," I said it in my first post. Copper > aluminum. But sometimes aluminum is good enough for your gun and load. Then there's no difference as far as you're concerned!

Well let me tell you that MY aluminum checks DO NOT fall off at 2400 fps and I've fired them much faster then that out of a 30-06 with a MUCH faster twist then what Larry is using on his XCB rifle. This is not to infer anything negative to what Larry is saying. I believe what he's telling us here. It just doesn't happen to me.

[gloob]

What's "much faster?" I believe my Lyman cast data load info lists ~1800-2200 fps for maximum loads in 308.

More importantly, what happened when you maxed out and suffered failure? If you haven't found that point on both types of checks, then you really don't know which one works better, do you? I admit I haven't done this, and that I don't know from my own experience. I'm going with Larry's data.

It takes a lot of time and range trips to do this kind of thing. I tried to shoot 2400 in 223, once, with a load some shooter had been cooked up for cycling an AR. The boolits ended up coating my flash hider. I just went back to lyman data at 1900 fps, which I found works with aluminum or copper. But that doesn't prove aluminum = copper.

Even if I tried, the difference might not be much if any in 223 with the 10 thous check. I would expect there might be a bigger difference in boolits with thicker checks.

[TD1886]

What's "much faster?" I believe my Lyman cast data load info lists ~1800-2200 fps for maximum loads in 308.

More importantly, what happened when you maxed out and suffered failure? If you haven't found that point on both types of checks, then you really don't know which one works better, do you? I admit I haven't done this, and that I don't know from my own experience. I'm going with Larry's data.

It takes a lot of time and range trips to do this kind of thing. I tried to shoot 2400 in 223, once, with a load some shooter had been cooked up for cycling an AR. The boolits ended up coating my flash hider. I just went back to lyman data at 1900 fps, which I found works with aluminum or copper. But that doesn't prove aluminum = copper.

Even if I tried, the difference might not be much if any in 223 with the 10 thous check. I would expect there might be a bigger difference in boolits with thicker checks.

Don't know why you mentioned loads for the 308, I did say the 30-06. They were a tad over 2800 fps.

Well if you are asking me what happened when "I" maxed out, well I didn't max out and nothing happened. I was pushing the 06 with that cast load to see what it would do. The one thing I don't like about my CZ550 is the groove is .309 . The second thing I don'w like is it's a hammer forged barrel and although some hammer forged barrels shoot very well, many don't.

I once tried to strip a 7mm cast bullet in a 7x57 Mause and the bullet was cast of lead. I couldn't do it and it really didn't lead the barrel. I'm not sure you can get a cast bullet to turn 360 degres plus in a barrel. Revolvers I've seen it happen.

[Larry Gibson]

Keep in mind many push cast bullets faster because of PPing and PCing. Both are a form of a "jacket" and do alloy higher velocity while maintain accuracy. My data refers to ternary alloy naked cast bullets that are just GC'd and lubed.

I have pushed PC'd GC'd cast bullets to 2800 fps and maintained usable accuracy at 100 yards. That was out of .223s and a 308W with 12' twists. However, with ternary alloyed naked, GC'd and just lubed bullets I've yet to see such. Yes, it is easy to get 2800 fps out of any '06 with any cast bullet. However, maintaining accuracy is another thing.

gloob, what are the specifics of that 2800 fps load, number of shots and what accuracy at what range(s)?

[gloob]

Don't know why you mentioned loads for the 308, I did say the 30-06. They were a tad over 2800 fps.


Just because the 308 numbers are the ones I looked at, when I last knew where my Lyman manual was. 30-06 has a bigger case and can theoretically get higher velocities with a lower pressure (like with jacketed bullets), but I would have guessed max cast velocity would be pretty much the same thing between the two, using the ideal powder for either.

You got 2800 fps in 30-06 with aluminum checks, first try, no experimenting with powders and alloys needed? Are you PC'ing, too? Is this your regular load? If not, did you put it on paper to make sure they're going straight?

edit: ^LArry, that was TD's post. I've yet to get a normal checked boolit to exit in one piece above 2200 fps.


I once tried to strip a 7mm cast bullet in a 7x57 Mause and the bullet was cast of lead. I couldn't do it and it really didn't lead the barrel. I'm not sure you can get a cast bullet to turn 360 degres plus in a barrel. Revolvers I've seen it happen.
TD, was that with a gas check? I don't think you can leave fouling in the barrel when using a gas check. Even when my cast 223 were leaving the barrel in a blast of molten lead, the bore was clean.

Boolits getting "stripped" by the rifling is something I don't really believe, yet. How do you know? Do you recover the boolit, after? And by the time rifling "stripped" a boolit, wouldn't it get gas cut all to heck and completely messed up beyond recognition? I imagine only half the boolit would make it out in a solid piece.


Yes, it is easy to get 2800 fps out of any '06 with any cast bullet. - Larry
Interesting. I thought the boolit was the limit, at some point, rather than case capacity. Hence the rise of larger and larger case capacity with smaller/faster bullets going hand-in-hand with the introduction of jacketed bullets. I've entertained the thought of a 22 Hornet, as potentially shooting just as fast as 223 with cast boolits but with less powder. But then the reality of more expensive cases makes that moot. Case capacity is potentially a bigger component than I thought. Now I really want to find my Lyman manual.


However, maintaining accuracy is another thing. Yes, this is what I meant. I mean, if you don't count accuracy, you can make any rifle shoot cast at least as fast as jacketed. Dunno how accurately you can chronograph a spray of lead droplets, though.

[TD1886]

Just because the 308 numbers are the ones I looked at, when I last knew where my Lyman manual was. 30-06 has a bigger case and can theoretically get higher velocities with a lower pressure (like with jacketed bullets), but I would have guessed max cast velocity would be pretty much the same thing between the two, using the ideal powder for either.

You got 2800 fps in 30-06 with aluminum checks, first try, no experimenting with powders and alloys needed? Are you PC'ing, too? Is this your regular load? If not, did you put it on paper to make sure they're going straight?

edit: ^LArry, that was TD's post. I've yet to get a normal checked boolit to exit in one piece above 2200 fps.


TD, was that with a gas check? I don't think you can leave fouling in the barrel when using a gas check. Even when my cast 223 were leaving the barrel in a blast of molten lead, the bore was clean.

Boolits getting "stripped" by the rifling is something I don't really believe, yet. How do you know? Do you recover the boolit, after? And by the time rifling "stripped" a boolit, wouldn't it get gas cut all to heck and completely messed up beyond recognition? I imagine only half the boolit would make it out in a solid piece.

First the 7x57. Yes with a gascheck. It should have been severely leaded, but wasn't. If it was leaded the gascheck wouldn't have take every bit of it. Also there was no grey wash or leading at the crown.

On the 06 I had been shooting gaschecks all along so can't really say first try. I was using RL22 powder. The accuracy was good enough for deer, but it wasn't what I wanted. I wanted an inch or below. So not the bullets weren't PP'ed. To tell you the truth I don't care a lot about PP bullets.

[Shopdog]

If you're having issue with them coming off;

Cpl ways to stop it dead in it's tracks are... roll crimping,is an easy enough process that you'll have to cut the shank off before it can be removed. The other isn't quite as "forever" but durn close.... use a 5C collet/closer and turn in the upper edge.

Good luck with your project.

[TD1886]

Okay I have done some tests to prove to you all that auto extracted fired cases are hotter then manually extracted cases. Test Rifle: M1A Springfield Nation Match Stainless barrel. Rifle Temp: 65 degrees. Ammo LC primed cases loaded with IMR 4064 powder and topped with Hornady 168 grain match bullets. First Shot Semi Mode: Case temperature was 110 degrees and that's after it flew through the air and landed on the ground and I walked over to it to gauge it. So it had some cooling time. Screwed the gas plug out of the rifle as it doesn't have a gas shut off system. Second Shot: Case temperature was 76 degrees and that's after I manually ejected it and gauged it as it was laying on the ground.

Our you fellows believing me now that semi or full auto extracted cases are hotter then manually extracted cases because the friction of them getting violently extracted and ejected from the chamber?

This is about all I can do to prove this to you all. I will be testing other firearms and calibers if you are interested.

[TurnipEaterDown]

The semi auto or full auto gun extracts the case from the chamber much faster than anyone can manually. Residual case temperature has a strong relationship to dwell time in the chamber and heat transfer from the brass casing to the chamber walls. Not so much about friction. The case does have higher residual chamber pressure during extraction in a semi or full auto than a typical manually operated gun like a bolt, pump, or lever, but then I never saw anyone run a bolt, pump, or lever at 1000+ rpm either.

[gloob]

you fellows believing me now

I figured you'd have deleted that post, by now. I never did quote it, so as to give you that chance after giving it 10 more seconds of thought.

You, yourself posted this, right after.

By the way one gram of powder produces about 3700 joules energy from high energy gun powder. There's is only one powder manufacturer that releases this type of data that I know of. You figure out who it is. While you are at figure out what the C or F degree of 3700 Joules is!!

Yes, you can start a fire by rubbing two sticks together. But if you do that at the same time as burning 10 grains of smokeless powder under your tinder, you might want to give some credit to the powder.

Measure the temp of your chamber while you're at it. Notice it heats up, too, but it will never get as hot as a freshly auto-extracted case. The chamber cools the case.

You could also try extracting an empty case out of your gun over and over. Tell us how hot it ever gets.

Giving physics lessons always goes wrong, on a gun forum. I know better than to try, but here I am:

Barring some potential extra friction from early/sticky extraction, the total amount of heat created by extracting a case slowly versus quickly is the same. This is the reason boolit friction can't make an entire boolit turn to mush, no matter how fast you shoot it (keeping barrel length constant). Faster velocity just means that same amount of heat from friction is dumped into the skin of the boolit in a shorter time, potentially softening/melting the skin before that heat is shared deeper into the core, and then allowing gas to jet past and melt the entire boolit. Higher psi will more likely force a leak and higher psi means the jet is faster, thus hotter (replaced by more hot gas as fast as that heat is absorbed by barrel/boolit).

I.e., if a substantial enough portion of the boolit melted/eroded to cause accuracy issues, that boolit leaked, period. And the portion of the boolit that was lost was due to a gas jet down the side. Unless you made a special gun with a 24 foot long barrel in order to melt a boolit through friction.

[TD1886]

I figured you'd have deleted that post, by now. I never did quote it, so as to give you that chance after giving it 10 more seconds of thought.

You, yourself posted this, right after.


Yes, you can start a fire by rubbing two sticks together. But if you do that at the same time as burning 10 grains of smokeless powder under your tinder, you might want to give some credit to the powder.

Measure the temp of your chamber while you're at it. Notice it heats up, too, but it will never get as hot as a freshly auto-extracted case. The chamber cools the case.

You could also try extracting an empty case out of your gun over and over. Tell us how hot it ever gets.

Giving physics lessons always goes wrong, on a gun forum. I know better than to try, but here I am:

Barring some potential extra friction from early/sticky extraction, the total amount of heat created by extracting a case slowly versus quickly is the same. This is the reason boolit friction can't make an entire boolit turn to mush, no matter how fast you shoot it (keeping barrel length constant). Faster velocity just means that same amount of heat from friction is dumped into the skin of the boolit in a shorter time, potentially softening/melting the skin before that heat is shared deeper into the core, and then allowing gas to jet past and melt the entire boolit. Higher psi will more likely force a leak and higher psi means the jet is faster, thus hotter (replaced by more hot gas as fast as that heat is absorbed by barrel/boolit).

I.e., if a substantial enough portion of the boolit melted/eroded to cause accuracy issues, that bullet leaked, period.

Gloob let's go after this at a different angle. Let's take a 45-70 case and resize it. Maybe you never paid a lot of attention to resizing cases other then how hard or easy they were to size and also hoping you don't stick a case. Well not that, but how warm the case gets sizing and extracting it. Get your 45-70 lubed and ready to resize and line it up to the die mouth. What I want you to do is ram it into the dies and extract it right away and fill the case and tell me if it's warm or not. Remember the dies is cold, it isn't buning any powder, and you're not shucking the case out of the die as fast as semi auto or full auto action.

On the joules of energy I never once said that powder didn't burn hot.

On your loading a case and extraction it over and over isn't going to do much because their isn't much friction since the case is loose in the chamber. I don't think that was a very good analogy on your part.

If you don't want to believe that the majority of the heat in an extracted case from a semi or full automatic weapon is from friction, well then that is your prerogative. To be sure I'm not talking about a 06 30 caliber machine gun running non stop in a Jap banzai attack on Iwo Jima in WW2 where the machinegun is so hot it's cooking off rounds.

[gloob]

I reload on a SS. I touch every case immediately after sizing. Never noticed any increase in temperature of my cases or die, TBH. There's definitely heat from friction, but it's insignificant in comparison to a powder charge going off right inside of the case.

The reforming of the case also creates some (very small) amount of heat. But in most properly functioning semiautos, the case is not reformed during extraction. So I think my "analogy" was fair. Do a mag dump, first, to heat the gun up. Then put a case in and jack it out as hard/quick as you can. I bet it won't be as hot as a case you manually eject gently but immediately after firing a cartridge in a cold gun.


On the joules of energy I never once said that powder didn't burn hot.


No. You said this. You're still trying to prove it.

do I really think an ejected cartridge case main heat source is friction, no, I know it is.

[TD1886]

I reload on a SS. I touch every case immediately after sizing. Never noticed any increase in temperature of my cases or die, TBH. There's definitely heat from friction, but it's insignificant in comparison to a powder charge going off right inside of the case.

The reforming of the case also creates some (very small) amount of heat. But in most properly functioning semiautos, the case is not reformed during extraction. So I think my "analogy" was fair. Do a mag dump, first, to heat the gun up. Then put a case in and jack it out as hard/quick as you can. I bet it won't be as hot as a case you manually eject gently but immediately after firing a cartridge in a cold gun.



No. You said this. You're still trying to prove it.

I know the main heat cause in an extracted case is friction. I said what I said to be sarcastic when I said no. So you can get off that kick because you don't have anything on me.

When friction welding of steels, the weld interface reaches temperature up to 1300 degs C.


With sizing 45-70 cases in the manner I described they are a little bit more then just warm.

[TD1886]

[QUOTE=gloob;5573322]I'm glad I didn't put you off, yet. I know I am annoying, and I'm trying to improve on that.


gloob you said that. Yup, you're right, you are annoying!! LOL

[archangel2003]

Many abrasives have aluminum in them. Ever see the term "aluminum oxide"? But with a gas check, there is hardly any bearing surface that could cause wear.

As far as the elasticity of aluminum, that may be true. But, copper can be the same way if it is not annealed properly. Several have written they anneal gas checks to make them dead soft, the same reason you anneal case necks so they won't crack or if you are manipulating the case for a wildcat.

Aluminum Oxide is not aluminum, it's an oxide of Aluminum and in no way the same thing.

[gloob]

The surface of aluminum oxidizes very rapidly, once exposed to air. Less than a second. Aluminum checks are covered in aluminum oxide. But the layer is so thin and smooth, the "grit" would be very high. Aluminum checks should burnish a new and rough bore, a bit. But nothing more would happen once all the sharp micro-points and edges had been smoothed.

Rifle barrels die from gas erosion in the throat. Pistol barrels can last practically forever. Shooting aluminum checks shouldn't really matter in any firearm.

[braddock]

The only thing I've noticed is when using the lee sizer pushing the aluminum gcs through can cause flashing round the base, whereas I don't get this effect with either brass or copper.
In the attached image the boolits go, from left to right185 grn round nose copper gc, 160 grn FP brass gc, 175 grn FP aluminum gc where the flashing I refer to is visible and 155 swaged wadcutter with aluminum gc with no flashing. All were sized in the same Lee 309 sizing die.
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[MUSTANG]

I believe that many are confusing Aluminum Oxide (a chemical compound) and Aluminum Corrosion (exposure to atmospherical impacts). Aluminum Oxide is either a manmade compound - or a natural occurring phenomena over many millennia.

I use Amerimax .014 Roofing material for most of my Gas Checks. Despite many, many, many thousands of rounds I have not seen any affects from the Aluminum Checks.


ALUMINUM OXIDE
(or Aluminium(III) oxide) is a chemical compound of aluminium and oxygen with the chemical formula Al2O3. It is the most commonly occurring of several aluminium oxides, and specifically identified as aluminium oxide. It is commonly called alumina and may also be called aloxide, aloxite, or alundum in various forms and applications. It occurs naturally in its crystalline polymorphic phase α-Al2O3 as the mineral corundum, varieties of which form the precious gemstones ruby and sapphire. Al2O3 is significant in its use to produce aluminium metal, as an abrasive owing to its hardness, and as a refractory material owing to its high melting point.


CORROSION BEHAVIOR OF ALUMINUM IN ATMOSPHERE
From the extensive weight-loss studies conducted around the world on aluminum corrosion rates of 0.03 to 4 µm/year have been reported. The corrosivity of a location would depend upon the distance the airborne salt travels, the direction and velocity of the wind, the frequency of the prevailing wind and topography of the coast and the expanse of seawater over which the wind has come. The salt content drops rapidly with increasing distance from the sea.

Loss of tensile strength can occur due to atmospheric corrosion. In rural area's atmosphere, the corrosion rate averages 0.03 µm/year (0.001 mils/year). In industrial locations, the corrosion rates average 0.8–0.28 µm/year (0.03–0.11 mils/year). In certain polluted environments, a higher corrosion rate of 13 µm year (0.52 mils/year) was obtained. Table 10.10 shows the corrosion rates of aluminum and selected aluminum alloys in different environments.

[bigjake]

Aluminum Oxide is not aluminum, it's an oxide of Aluminum and in no way the same thing.

agreed!!

[gloob]

In practice, aluminum is very corrosion resistant. It doesn't rust when exposed to water and air, like steel.

But pure aluminum is very reactive. It's so reactive that as soon as it is exposed to air, it oxidizes near instantly, forming aluminum oxide. But this layer is super thin before it blocks the pure aluminum underneath from air.

An aluminum gas check is completely covered with aluminum oxide.

To be much of an abrasive you need chunks of aluminum oxide through and through. A nanometer thick coating of aluminum oxide won't abrade your barrel.

[brasshog]

Although I have used gator gas checks from Sage for many years and I actually prefer the look of copper I have been making my own aluminum checks out of .014 flashing with great success.

[gwpercle]

Buy whatever is cheapest , fits your boolit best or what is "In Stock"

Sage will send you a sample pack to check size / fit ... checks that fall off the boolit are just a royal pain ... buy checks that snap on and stay on ... alumn. or copper , it doesn't really matter ... To me "Fitting" is more important than alumn. or copper .
Gary