Copper or Aluminum

[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.

[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.

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/arc...hp/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?