Homemade Gas Checks

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sluggo posted this 11 August 2026

I have his .30 gas check maker. It works as advertised. It kind of comes down to using my reloading time for making checks or other reloading activities. I could not tell the difference between factory made or his. It seems like factory made gas checks unlike primers and powder are usually available. As long as factory made checks are available I will use them. Pat does make a plain base check maker. It sounds interesting but I have not tried it yet.

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Spindrift posted this 11 August 2026

The Pat Marlin check makers have worked well for me. Where I live (Norway), gas checks have become hard to find; hence the need to make them myself. There is a little learning curve involved. A few pointers:

1) Material. 0,3mm aluminum works well for .30

2) Cutting strips. First, get a good quality paper cutter. Preferably all-steel. Second, make gauges: a rectangular piece of metal where you cut a slot in one end, with a depth corresponding to your desired strip width. This makes the process of cutting strips quick, accurate and safe. Keeps your fingers away from sharp stuff.

3) Installing the die. The stacked tolerances of die and press production might cause the cutter to bind in certain positions. Try to rotate the die until you find a position where the cutter moves freely inside the die body. Then, leave it without fixating it with a lock ring. A little play allows the system to self-allign under force. This way, you reduce wear and cut better discs.

4) The discs might look flat, but they aren't. One side is (very slightly) concave, with rounded edges. The other side is convex, with burred edges. When you feed the discs into the forming die, place them with the burred edge facing up. Give the forming die a little rattle. The disc should self-centre easily. And the burred edge will end up facing the shank of the bullet, aiding in grip. If you can't feel a burred edge, then two discs have mated, burred edges facing.

My home-made aluminum checks have better grip than commercial alu checks. I have not been able to find any difference in performance as compared to copper checks. The workload of making them is partially offset by the ease by which they are installed. They slide on the shank almost like a slip-on check, yet grip the bullet like a crimp-on.

As for plain-base gas checks, the short answer is "they work".

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Wm Cook posted this 11 August 2026

I appreciated both your comments.

Mike’s position is that it works but if over the counter checks are available it’s not worth the effort. Henrik’s take on it is if over the counter checks aren’t readily available you’re up a creek if you can’t make your own.

The pandemic coupled with the war in Ukraine messed up supply and material cost for all of us. I think checks, like Linotype has doubled in cost. And primers, powders have skyrocketed, and LR primers just recently became readily available. If 5744 was ever produced it would cost over $600 a jug. Someone recently mentioned RL 17 selling for $90 a pound.

During the pandemic I was caught short on gas checks. They were not readily available. Everyone that didn’t plan ahead panicked and bought up anything and everything. At that time I guess gas checks just got caught up in the madness.

I’m set with powder & primers for my duration. I’ll continue to have a years worth of gas checks on hand but keep the Martin GC die as a backup.

What I found interesting was no opinion one way or the other regarding home made aluminum gas check & accuracy.

A second was Henrik’s comment about putting checks on plain based bullets. Thanks, Bill Cook.

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Sevenfan posted this 11 August 2026

I bought BFB one step check makers, have them for 4 calibers. Can find them here if interested - https://bfbmachineworks.com/

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tomme boy posted this 12 August 2026

I use the bfb in 30cal. It is perfect. I also have one of his 44pb one that will not make the checks stay on. They are not tall enough to work.

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connecticut_red posted this 14 August 2026

Just a data point, I've been meaning to email BFB for a while. I got on their list for a .452 gas check maker in the middle of last September and never heard from them again.

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Sevenfan posted this 4 weeks ago

Blair was very responsive to my order requests, only exception was during the tariff games between US & Canada, had to wait longer for that to settle out but got my check makers soon as the dust settled. Was wrong, I have 5 of them in 6.5mm, 7mm, 30, 35, & 45cal.

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Wm Cook posted this 4 weeks ago

I admit this topic is just unnecessary minutiae taken to the n’th degree, but I’m still wondering if anyone has any first hand experience with homemade gas checks and their effect on cast accuracy. Either pro or con. Thanks to everyone who chipped in. Bill Cook.

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tomme boy posted this 4 weeks ago

I have not seen any difference between the ones I make and Hornady copper checks.

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JeffinNZ posted this 4 weeks ago

I have not seen any difference between the ones I make and Hornady copper checks.

I have in my .30-30 bolt gun shooting 40-1 alloy. Alum check does not shoot anywhere near as accurately as a commercial check on the very soft alloy at 1700fps. I suspect the more aggressive grip of the copper cup is needed to keep the soft alloy square.

Cheers from New Zealand

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Wilderness posted this 4 weeks ago

A friend made some aluminium .30" gas checks for me. All I can say about them at this stage is that they seem OK with hard alloy #311578HP EXCEPT that any attempt to pull a bullet results in a gas check staying in the case neck. Hornady are OK in this regard.

I'll know more when I put some across the Oehler chronograph - if the screen protectors get hit I'll know they're coming off in flight.

You are only as good as your library.

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Sevenfan posted this 3 weeks ago

I have not seen any difference between the ones I make and Hornady copper checks.

Matches my experience as well, haven't tried aluminum yet.

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Larry Gibson posted this 3 weeks ago

I have two Pat Marlin GC makers, a 35 cal and a 45 cal PB. I use .014 aluminum with the 35 and .006 aluminum with the 45 PB. Both make GCs that give acceptable accuracy for the pistol/revolver bullets I use them on. I haven't really conducted an actual accuracy test though.

I use another type of GC maker to make 30, 31 and 8mm GCs. I use the .014 aluminum and .012 copper to make GCs in those. In milsurp and sporting rifles I've found the aluminum GCs give comparable accuracy in 10" twist barrels upwards of 1900 fps compared to Hornady GCs. Above 1900 fps some recovered aluminum GCs that flew off and were recovered short of 50 yards showed they had fractured and split along the rifling marks. That did not happen until around 22-2300 fps in 12 and 14" twist barrels. The .012 copper GCs gave comparable accuracy to Hornady GCs through 2500+ fps. I only use Hornady 30 cal GCs in mt Palma and 30 XCB rifles up through 3000 fps. Above 3000 fps some of the GCs were shed out of the muzzle.

LMG

Concealment is not cover.........

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Wm Cook posted this 3 weeks ago

Thanks Larry. As I understand it, the .014 aluminum is recommended by Pat and from what you say things become dicey after 1900fps with a 10 twist. If one was conservative and start to be concerned that at ~1700/1800fps it raises concerns about using of aluminum for accuracy with fast twist barrels.

I’m guessing that the manufacturer of your another type of gas check maker you use might be BFB Machine? I understand that die might be better suited to cutting the .3mm copper sheating. Pat makes no bones about his die being designed for using the .014 aluminum. Which. in and of itself, would cover the practical velocity and accuracy range of 90% of cast shooters with the caveat that the faster the twist, the more risky the outcome.

I appreciated your response. Bill Cook.

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Larry Gibson posted this 3 weeks ago

I've had a BFB on order but, like everyone else notes, delivery is still dicey given the tariff/political situation.

My 30/31 and 8mm GC tools were made for me years ago by a member on the boolit forum. I've lost contact with him and don't remember his name. I'm hoping he'll make contact with me. They are simple tools to use with a mallet but I use an arbor press. I have made several thousand with with perfectly satisfactory results. I'm sure he could make and sell them here and on the other forum.

LMG

Concealment is not cover.........

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JeffinNZ posted this 3 weeks ago

Thanks Larry. As I understand it, the .014 aluminum is recommended by Pat and from what you say things become dicey after 1900fps with a 10 twist. If one was conservative and start to be concerned that at ~1700/1800fps it raises concerns about using of aluminum for accuracy with fast twist barrels. I’m guessing that the manufacturer of your another type of gas check maker you use might be BFB Machine? I understand that die might be better suited to cutting the .3mm copper sheating. Pat makes no bones about his die being designed for using the .014 aluminum. Which. in and of itself, would cover the practical velocity and accuracy range of 90% of cast shooters with the caveat that the faster the twist, the more risky the outcome. I appreciated your response. Bill Cook.

Depends on the calibre. 0.3m/.014inch is prefect for .30cal however for .22/6mm you'd want 6-8 thou, .25-.27, 10-12 thou.

Cheers from New Zealand

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Sandman` posted this 2 weeks ago

Has anyone had any experience with Pat Marlin’s gas check maker? I bought a .30 cal die during the COVID crisis and never used it. I came across it while I was in the shop today and it got me thinking. Thanks, Bill C.

Dont have any experience with Pat Marlin. Seamus Sage from Sage's Outdoors located in Selma, AL has a place where he sells his home made gas checks or Gator gas checks. I have been very happy with his home made copper gas checks, about $36.00 for 1000. They fit my .308 bullet well and crimp on nicely. He has several different sizes and aluminum checks as well.

https://www.sagesoutdoors.com/

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Homemade Gas Checks

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