View Full Version : Gas Checks

March 17, 2012, 09:49 PM
When do you use them? and what is the difference between aluminum and brass checks? this would be for 30 cal bullets

March 17, 2012, 10:27 PM
I would think about using them when pushing a bullet over 1000 fps. The difference between aluminum and brass is price. They both perform as well.

March 18, 2012, 12:03 AM
You can get properly sized boolits to run up to 1500 to 1600 fps without leading or checks.

March 18, 2012, 08:42 AM
Yup. My rule of thumb is about 1400 FPS + I strap on a gas check. I use gas checks rarely because they are expensive and cumbersome to put on if you shoot alot. I only gas check my .223, 500 SW, and various 30 cal rifle loads (7.62x54r, 7.5 swiss). I don't gas check 32 auto, 380, 9mm, 38, 357, 40, 10mm,44 spl, 44mag, and 45acp. Boolit fit is king. For smaller caliber, high pressure rounds I prefer to size .002" over groove diameter. 38/357 on up I size .001" over. You will find out what works for you. Good luck!

March 18, 2012, 09:55 AM
For all the many years I was a member of the Cast Lead Bullet Association and received the Fowling Shot magazine, I noted that all the competitors (modern .30 cal. rifles), used gas checks on their rifle bullets despite the fact that they routinely only used loads that produced the velocity of 1100 fps (around the speed of sound). These competitions were focused on producing the most accurate loads possible. That fact implies that despite the fact that you can shoot bullets without gas checks and at higher velocities, for top accuracy, it would seem they are an advantage. Now, the data taken from competitions as listed in the Fouling Shot, has nothing to do with hunting bullets, if that is your purpose.

March 18, 2012, 08:44 PM
Dahermit confirms information I have heard too. The base of the bullet is important to accuracy. Some molds are nose pour, where the sprue is cut at the nose or front of the boolit. This ensures the bases are crisp, flat, and consistent. I don't own any of these types of molds. I can't speak from experience.

March 18, 2012, 08:54 PM
I bought two lyman molds, the 311299 and the 311284. Both of these molds are popular with the cast bullet crowd and they are recessed for gas checks.

I shot them without gas checks and accuracy was horrible. Like would not stay on a 8.5 X 11" paper at 100 yards horrible.

I shot them with gas checks and the accuracy was much better.

I have no idea why, but I will go with what works. ;)

March 18, 2012, 10:30 PM
I use gas checks on my 32 Special, 35 Rem and some 45-70 hunting loads because they run 1600-2200fps. On my pistol cartridges and 45-90 (blackpowder) I see no need for gas checks. I'm working with plain-based bullets in the 45-70 around 15-1600 but like the GC bullet better.

David Wile
March 22, 2012, 01:14 AM
Hey folks,

I started using copper gas checks 50 years ago when they were cheap as dirt. As years went by, gas checks went up in price until they were quite a significant cost to me.

About five or six years ago, I heard about making my own aluminum gas checks from soda cans with a FreeChex tool kit sold by a fellow named Charlie Darnall out in California. Considering the price of copper gas checks, I bought one of the FreeChex kits to see how they worked and how the aluminum gas checks worked. I got a tool set for 38 caliber, started making gas checks for my .357, and found out they worked just fine.

The first version of the FreeChex used a punch to punch out aluminum discs from a soda can, and then a mandril and die to form the gas check from the disc. It was time consuming but I could do it while watching TV in my recliner. Then Charley came out with his FreeChex II tool set. It was a little more expensive but cut the discs without having to use the punch and was a little bit faster. I ended up with two of the original FreeChex tool sets for two calibers (.357 and .30) and two of the FreeChex II tool sets for two other calibers (.44 and .45-70), and I still use both types of sets to make my aluminum gas checks. Later, Charlie came out with his Freechex III tool set that works with a cheap arbor press and makes checks faster than you can believe. Each cycle of the handle makes a finished check in one step that falls through the bottom to a collection pan. I never tried the FreeChex III, but I saw it work on a You Tube thing where a fellow is feeding the machine from a continuous coil stock. You simply cannot believe how fast it works.

The FreeChex III is to be use with either copper or aluminum thicker coil stock you can get at Home Depot rather than using aluminum soda cans. I already had tool sets for the four calibers I use, so I never tried the FreeChex III tool set. I also liked the idea of using scrap soda cans for my gas checks.

And in case you are wondering, no, aluminum gas checks do not form aluminum oxide and ruin my barrels. The aluminum is coated on both sides, and when placed on the bullet which is sized and lubricated, they are well lubricated and not about to oxidize.

Best wishes,
Dave Wile