Aluminum gas checks

[dddddmorgan]

Can you use the aluminum gas checks the same as the copper?

I want to order some from Sage and they're out of copper but have aluminum.

[bimus]

I have had no problems with sage aluminum gas checks mostly used on 30carbine.

[pworley1]

I have not noticed any difference except the price.

[MUSTANG]

Have not used a copper gas check for about 20 years now. Only problem I ever had is when seating a cast boolit base below the neck and trying to break down a loaded round with Impact Boolit Puller; a couple of times the Gas Check pulled loose and remained in the neck (pulled by drilling a hole, inserting screw ad pulling gas check with liters).

[FrontSite]

Have not used a copper gas check for about 20 years now. Only problem I ever had is when seating a cast boolit base below the neck and trying to break down a loaded round with Impact Boolit Puller; a couple of times the Gas Check pulled loose and remained in the neck (pulled by drilling a hole, inserting screw ad pulling gas check with liters).

I notice the same thing (gas check staying in the cartridge). I use a shortened bicycle spoke to punch the check sideways, grasp it with a 6" forceps and tug it free of the case. i didn't like the drilling part as i had metal bits in the salvaged powder.
Try it see if it works for you.

[FelixTheCat]

I would be wary of using aluminium in a projectile. Aluminium may be soft, but the oxide layer that inevitably forms over the metal is very hard indeed. Aluminium oxide is a main ingredient in many abrasives.
I know the wear rate in the chambers of aircraft cannons from using aluminium cartridge cases is significant. The weight saving is however great enough to justify the expense of having to change barrels regularly. (... and the airforce has Deeep pockets!)

[MUSTANG]

I would be wary of using aluminium in a projectile. Aluminium may be soft, but the oxide layer that inevitably forms over the metal is very hard indeed. Aluminium oxide is a main ingredient in many abrasives.
I know the wear rate in the chambers of aircraft cannons from using aluminium cartridge cases is significant. The weight saving is however great enough to justify the expense of having to change barrels regularly. (... and the airforce has Deeep pockets!)

FelixTheCat:

I encourage you to review the many posts and pages on the use of Gas Checks made from aluminum. The concerns you postulate HAVE NOT proven to be issues for myself and many, many others. I have fired many thousands of rounds through my Remington 700 in 308 Winchester with velocities of 1700 to 2200 FPS using Aluminum Gas checks and there is no visual affects to the barrel - nor, has there been any detriment to the accuracy potential of the Rifle.

It would be interesting to hear more information on your reference to wear rate on the aircraft cannon (Chambers you mentioned). If it is the Chambers as you cited; this would indicate an Aluminum cased cartridge (20mm or 30mm?); & the case being the wearing point in the chambers you cite - not the barrel/s of the Gun.

[longbow]

While it is true that aluminum oxide is abrasive, the layer forming on a gas check is very, very thin and fine, not like aluminum abrasives. Also, in most cases the gas check is put onto the base of the boolit then is run through a sizer/luber so the surface is being scraped in the sizer and lube is being put over it. I wouldn't claim that removes all the aluminum oxide and I also can't say I have shot enough aluminum gas checks to show any wear difference between aluminum and copper.

I have read warnings about the abrasiveness of aluminum gas checks for many years but I have as yet to experience, or read of anyone who has experienced, noticable barrel wear from them.

but I am with Mustang, I do not believe it is a problem but to each their own.

YMMV

Longbow

[405grain]

I make 30 caliber aluminum gas checks from Ace Hardware flashing using a Pat marlin's check maker. Since I'm powder coating the bullets anyway, I just PC over the gas checks, and if there were a problem with an oxide coat (which there really isn't) that would negate it.

[gloob]

Well, if you want to worry over nothing, you could also be think about what color PC to use. Finely ground metal oxides are used to add many of the colors, and some of them are harder than barrel steel.

[TurnipEaterDown]

I suspect that any abrasion concern by the aluminum oxide particles is negated by their size -- nano meter range (one source states atmospherically oxidized particles are ~ 4nm). So small that the effect on a firearm bore would have to accumulate over a long time to discern, and very easily "lost" in the lubricant film thickness of either the bullet lube or the paint (powder coat) barrier commonly used with a cast bullet.
eg. Yes, abrasive as a particle, unlikely to effectively abrade the bore due to characteristics of the system. Nano-meter --> 1/1000 th of a millimeter. Millimeter is ~ 0.004 inch, so these particles are on the order 0.000016 inch.

[JonB_in_Glencoe]

Most aluminum used to make GC's has a coating...like lithograph plate.

[elmacgyver0]

I will most likely be dead before aluminum gas checks wear out my barrels, then I won't care anymore.
Nuff said???

[2TM101]

I will most likely be dead before aluminum gas checks wear out my barrels, then I won't care anymore. Nuff said???

Anyone make these out of regular soda cans? I make percussion caps that way. I don't see how the thinner aluminum would degrade the performance any.

[Ben]

Might be a real good idea to read about using aluminum to make your own gas checks. I think you'll quickly see that pop can thickness aluminum is useless for making gas checks. It has some limited use for making plain base bullet gas checks.

[MUSTANG]

Anyone make these out of regular soda cans? I make percussion caps that way. I don't see how the thinner aluminum would degrade the performance any.

I have been using the Amerimax Aluminum Flashing that is 0.014" Thick. (4 inch x 50 foot roll). Have used it for at least 10 years on dozens of different .30, .224, and 7mm cast boolit designs successfully. The 0.014 seems to be the ideal thickness for making checks in these calibers (my experience). Keep in mind one will want 0.014 inch thick material (Amerimax Mfr #68104).

Ace Hardware carries it: https://www.acehardware.com/departments/building-supplies/roofs-and-gutters/roof-flashings/58012

Amazon also carries: https://www.amazon.com/FLASHING-ALUM-AMERIMAX-MfrPartNo-68104/dp/B0009SQFTS/ref=sr_1_3?crid=1EF8EU9FO7TW8&keywords=Amerimax+flashing+4+in.+W+X+50+ft.&qid=1705018419&sprefix=amerimax+flashing+4+in.+w+x+50+ft.%2Caps%2 C382&sr=8-3

[TurnipEaterDown]

Most aluminum used to make GC's has a coating...like lithograph plate.

The oxidation will be there before the coating is ever applied. Aluminum oxidizes to a protective film in milliseconds when exposed to air. As a friend who has worked w/ aluminum in forgings and castings for for mass produced parts over decades told me: you have never seen aluminum that wasn't oxidized.

Under the coating, and nowhere as large as the coating thickness. Probably never touches the bore.

[gloob]

I have been using the Amerimax Aluminum Flashing that is 0.014" Thick. (4 inch x 50 foot roll). Have used it for at least 10 years on dozens of different .30, .224, and 7mm cast boolit designs successfully. The 0.014 seems to be the ideal thickness for making checks in these calibers (my experience). Keep in mind one will want 0.014 inch thick material (Amerimax Mfr #68104).

Ace Hardware carries it: https://www.acehardware.com/departments/building-supplies/roofs-and-gutters/roof-flashings/58012

Amazon also carries: https://www.amazon.com/FLASHING-ALUM-AMERIMAX-MfrPartNo-68104/dp/B0009SQFTS/ref=sr_1_3?crid=1EF8EU9FO7TW8&keywords=Amerimax+flashing+4+in.+W+X+50+ft.&qid=1705018419&sprefix=amerimax+flashing+4+in.+w+x+50+ft.%2Caps%2 C382&sr=8-3

14 should be perfect for 30 cal. 224 gas checks are supposed to be 8-9 thousandths. That's what my Hornady checks measure. But 13-14 thousandths will fit on there pretty good, too.

There's a sticky at the top of this subforum. It shows shank size for common calibers. If you subtract the shank size from sized bullet OD, divide that by two, then add 2-3 thous, you'll get nominal gas check material thickness. But of course, your own mold, gas check die, and sizer die might work as good or better with a non-standard thickness.

Roof flashing can be had in 0.008-9, as well. This is what I use for 223 checks. The 14 thous stuff probably works better, but they don't go on as easily, requiring some time and fiddling to force them on all the way, with my mold. With the 8 thous material, I can crank out boolits.

Going by the shank sizes, 7mm bullet checks should be 20 thous thick! 14 thous doesn't even make up the difference between OD and shank size, leaving 3 thousandths of gap all the way around. 14 thous checks surely work much better than nothing, but not as good as they should.

30 cal, (308-284)/2 = 12, plus 2 = 14 thous
7mm, (284-250)/2 = 17, plus 3 = 20 thous
277, (277-253)/2 = 12, plus 2 = 14 thous
6.5, 8 thous
223, 8 thous

It's a bit curious that 7mm uses such a thicker check than the larger 30 cal. I wonder if cast bullet velocities are generally a bit higher with 7mm vs 30 cal or 277 (277 seems to also use the same check thickness as 30 cal).

Just measured one of my Hornady 7mm checks, and it's 20 thous on the nose. They fit my boolits like a glove.

I believe 17 thousandths is another common gas check thickness. Not sure if there are any others. 8, 14, 17, 20.

[2TM101]

At the moment I have no bullet molds for gas check bullets so I can't use regular ones.

I had never heard of a plain base gas check until you mentioned it, but now I am very interested in making and using those

[gwpercle]

At the moment I have no bullet molds for gas check bullets so I can't use regular ones.

I had never heard of a plain base gas check until you mentioned it, but now I am very interested in making and using those

Sage's Outdoors sells the Plain Base Gas Checks made to go onto plain base boolits , on their website are instructions and tips for getting them attached proberly to the base of a bullet ... there are some tricks to getting it done correctly .
www.sagesoutdoors.com
Check them out !
Gary

[fg-machine]

I am firmly in the not worried about wear crowd .

What I have noticed with aluminum checks is they don't seem to stay on the shank quite as well as copper does if your using a harder alloy . I had this same issue back when you could still brass checks .

What it boils down to is i get a "flyer" a little more often then I used to when using copper and on occasion I'll find a shiny gas check in the lane between bench and berm .

Don't take any of that as me bashing aluminum checks , I haven't bought copper since sage started selling aluminum.

[parkerhale1200]

I am making my own alu gs.
I did not see any difference in the barrel and end result regarding copper or brass.
Alu is cheaper, easier on my tools and preforms the same.

I also shoot 308 without gs full jacket loads...with no need to clean.
Brings us to the purpose of the gs itself.
I believe that is a other tread and much debated on this forum.

Go with alu and dont lose a second of sleep, what is the worst that could happen?????a extra cleaning session.

[parkerhale1200]

I am firmly in the not worried about wear crowd .

What I have noticed with aluminum checks is they don't seem to stay on the shank quite as well as copper

Yes the problem with alu checks.
You need to do it twice thru the lubasizer.

First a "dry run" to make what ever amount you want, then lube.
The problem is that alu is to soft to let the grease stay out. so it will let the grease in, thus a lose gs and possible a hole extra on the target(-:
Sorry you have to size twice, one dry and one with pressure on the lube.
Works for me perfect.
I also dont think alu gs will hold in a star sizer.
Most sizers are pressing on the bottom, thus creating extra to let the gs stay on.
Sorry for my bad English, i really hope this was helpful for you.

[2TM101]

I will use gas checks if I can make them myself, and there is an advantage to it. I can even make them out of Copper as I am now doing percussion caps that way. For that matter if a gas check, powder coat, and lube used together gets me up to jacketed bullet performance I will do all three.

[gloob]

If the check is made to fit properly to the shank and it's the right material thickness to swage the shank 2-3 thous as it crimps, it will seat and stay on tight. Some of the aluminum checks are made with slightly different thickness and dimensions.

Also works if the shank is made to fit to the check. I swage a gas check shank onto my PB bullets so that the checks go on consistently.

I've found 2 ways a gas check easily pulls off the boolit and will fall off in flight. One is if the check material is thinner than the difference between shank diameter and bullet diameter. The other is if the ID of the check is too small for the shank. Then the sizer squeezes the mouth of the check to the boolit while there's a large pocket of air between the bullet and check, so it's barely hanging on.

[Dan Cash]

I think some aluminum gas checks are too hard which increases their spring back and makes them prone to fall off the bullet shank. I have anealed my check material and fine the resulting gas checks seem to griip the bullet better.

[parkerhale1200]

I will use gas checks if I can make them myself, and there is an advantage to it. I can even make them out of Copper as I am now doing percussion caps that way. For that matter if a gas check, powder coat, and lube used together gets me up to jacketed bullet performance I will do all three.

i dont powder coat, and still i shoot pb's at full jacket speeds with alu checks.
44mag even without gaschecks at full jacket speed.
It is all in the hardness and tight fit of the boolit.
I shoot 308 with gaschecks, not for fouling but for accuracy.
For my ar15 the same, ps still no fouling in my gas pipe after almost 10.000 shots.

Get over your cold-water fear and dive in(freely translated Dutch saying, positive meaning btw), if you lived close by i would invite you.

[parkerhale1200]

I think some aluminum gas checks are too hard which increases their spring back and makes them prone to fall off the bullet shank. I have anealed my check material and fine the resulting gas checks seem to griip the bullet better.

Its not about the hardness(alu is softer than copper btw) i think you are referring more to the memory of the material.
i think also you need a slighter thicker aluminium sheet.
Soda cans are to thin.

Anealing is to "reset" the materials memory and to softening the material up before the next stage.

[405grain]

"For that matter if a gas check, powder coat, and lube used together gets me up to jacketed bullet performance I will do all three."

It's not realistic (or desirable) to expect jacketed bullet performance (velocity) from cast bullets. From a hunting aspect, cast bullets do not have a copper jacket that needs to be overcome for the bullet to expand. Cast bullets expand normally at much lower velocities, and would probably come apart violently with little penetration if fired at jacketed velocities. If cast from a hard enough alloy to get good penetration at high velocity they would probably lack good expansion.

From a target shooting aspect, fired at jacketed velocities cast bullets would be spinning at an rpm that exceeds their tolerance for good accuracy. Generally cast bullets begin to loose accuracy once velocities start going above 2000 fps. There are some specific target cartridges, load combinations, and barrel twist rates that can allow for higher velocities, but these are in specialized target rifles build for competition. As a general rule, for best results with most rifles (both for hunting and target shooting) velocities should be at around 1950 fps or less. There are always examples where people can load a little higher, but these are usually the exceptions, not the rules. Cast bullets work great when used in their best range of velocity.

[2TM101]

"For that matter if a gas check, powder coat, and lube used together gets me up to jacketed bullet performance I will do all three."

It's not realistic (or desirable) to expect jacketed bullet performance (velocity) from cast bullets. From a hunting aspect, cast bullets do not have a copper jacket that needs to be overcome for the bullet to expand. Cast bullets expand normally at much lower velocities, and would probably come apart violently with little penetration if fired at jacketed velocities. If cast from a hard enough alloy to get good penetration at high velocity they would probably lack good expansion.

From a target shooting aspect, fired at jacketed velocities cast bullets would be spinning at an rpm that exceeds their tolerance for good accuracy. Generally cast bullets begin to loose accuracy once velocities start going above 2000 fps. There are some specific target cartridges, load combinations, and barrel twist rates that can allow for higher velocities, but these are in specialized target rifles build for competition. As a general rule, for best results with most rifles (both for hunting and target shooting) velocities should be at around 1950 fps or less. There are always examples where people can load a little higher, but these are usually the exceptions, not the rules. Cast bullets work great when used in their best range of velocity.

Makes sense. I don't need max performance, its more my wanting to see how good a bullet I can actually make. I do not have any bullet molds for gas check bullet and at present could only do the plain base aluminum ones, which I would do mainly because its something new I have not tried yet. I do not *need* the better performance. In truth I powdercoat so I do not have to handle exposed lead, the fact it makes the bullets better is a plus.

What got me started on this is I have a lot of military surplus ammunition that is steel core and the ranges do not want me using it out here. I want to be able to pull the bullet and replace it with something I can make that will still work OK, and I figure I need every tool I can use to do that.

[2TM101]

I've found 2 ways a gas check easily pulls off the boolit and will fall off in flight

I thought a gas check was like a shotgun wad or a sabot. Does it really matter if it comes off once its out of the gun?

[gloob]

I thought a gas check was like a shotgun wad or a sabot. Does it really matter if it comes off once its out of the gun?

Depends on why it fell off.

If it was barely clinging by the mouth, then that's bad. When you fire the gun, the check doesn't get pushed onto the bullet. It just gets mashed in, inside out. So there's no bullet in there to press the sides of the check into the grooves. The check doesn't help to seal the gases and it falls off after the bullet exits. But it still cools jets of gas that are blowing past the first leaks in the boolit.

[gloob]

https://i.imgur.com/1DMue6y.jpg

Here's a picture of some of these inside-out checks I recovered. I knew the checks weren't seated consistently and the OAL's after seating the checks was all over the place. I had already come up with a better way to seat the checks. I just wanted to see what would happen.

There are no rifling marks on these fallen-off checks.

[405grain]

Gas checks need to crimp on the base or heel of the bullet. They become part of the bullet. Their main job is to prevent hot high pressure gas from leaking past the bullet. If that happens, the gas will vaporize lead off of the surface of the bullet. Once the bullet exits the barrel and the gas cools that vaporized lead will condense and begin plating on the inside of the barrel. Once this thin layer of lead plating builds up enough it will start galling against bullets as they pass down the barrel, smearing lead inside the bore. Before very long you'll have barrel leading. Gas checks help prevent the gas blow-by that starts this process.

The gas check also strengthens the base of the bullet so that it is less likely to deform under high pressure. Uniformity of the bullets base is more important to accuracy than the nose is, so gas checks help bullets retain accuracy at higher pressures and velocities. Generally, non-gas checked bullets preform well up to around 1400 fps, and sometimes can get to 1500 fps before they start getting into trouble. Moderate velocities with plain based bullets can be quite accurate.

If a gas check comes off the base of a bullet in flight, unless it just plain falls off, it is unlikely that it will come off uniformly. If the gas check gets torn off like prying the lid off of some container the bullet will become unstable and will wobble in flight. This won't be doing accuracy any favors. Around 120 years ago, when gas checks were first being experimented with, they were designed to fall off in flight. This didn't always work so well because sometimes they didn't. It was soon decided that it was better if the gas check was designed so that it would stay with the bullet during it's flight. Fun fact: the first cast bullet to be designed to use a crimped on gas check was the Lyman #311284 for use with the 30-40 Krag.

[Gunslinger1911]

I ran plain base pop can alum gas checks (Pat Marlins) ever since he came out with them. Nary a problem.
Solved a few issues over the years.
Thousands of rounds down range with alum GC.
I would guess the military issues with alum come from the high rate of fire, ie heat (like 4000 rounds per min)
For me, powder coating has replaced GC's. Think 125g .357 at ~2000 fps - no leading !!!! (but, WHAT a ball of fire !!!)