Explanation of the Theory and Engineering behind Checkmaker™ Gas Check Forming Dies

I got an email from a customer the other day who wrote:

“I got the Checkmaker™ and it’s good at punching “miniature bottle caps” from .010 copper. I would like to return this thing for a refund, the tool doesn’t do as advertised.”

Over the years, many seasoned cast shooters and myself here have found bottle capping to improve accuracy, so if your metals are not creating a smooth top end on your gas checks, you can relax. The proofis in the shooting performance.

This being the first email of it’s kind received got me thinking. I realized that after all this time and now several dies in use by shooters not everyone has followed my development of the die design and have seen the results we have obtained during the process.

When I set out to design a gas check forming die, I wanted a design that truly made it easy for the user to manufacture his own gas checks, and match the accuracy of factory offerings. Eliminate the need to buy factory checks entirely. I took a careful look at the designs that had been sold years ago, and the design currently on the market- the problems, the benefits, and the desires of the shooters using them.

What I found was guys having problems with things like gas check fit and having to use super glue. Lopsided checks. A limited narrow range of metal material thickness choices that could be used. A limited narrow range of fit from various shank sizes within a caliber, and the need to use a mallet and round punch, or buy an arbor press. Fewer shooting reports and no one reporting accuracy matching factory gas checks.

My first thought was, “Why not design gas check dies like reloading dies, and use what everyone already has… our reloading press?”. I wanted to make my own checks at the reloading bench and not have to bang on it with a mallet. Having experience with using round hole punches for other needs, and knowing what a pain they can be to sharpen and keep sharp, I didn’t want to go there either.

As I progressed and tested designs in R&D for weeks on end, and bouncing ideas off of a dear friend of the family who’s a talented machinist, I knew I was close when I loaded some rounds up for my circa 1978 Ruger #1 in 300 Winchester Magnum.

This rifle is a copper tack driver- I mean it will put the bullet where you want it if you’re man enough to hold it there. Problem for a hopelessly addicted cast shooter is the 300 Win Mag scares lead out the door. They just didn’t mix well for me, no matter what I tried short of using Lino, and I don’t care to use linotype. May as well melt copper for that matter… LOL.

So when putting my first 30 caliber .010 copper formed gas checks from the official Checkmaker™ design, the current design as now offered to the test I thought let’s pull out the old Ruger #1.

I have some great powders including some very good 4895 mil surp and other mil surps to play with. Powders that would be the “go-to” speeds for such purposes, but this time I pulled a load from the good old Lyman Cast Bullet Handbook, and employed one of the fast burning loads for my cavernous 300 Win mag belted brass. Previous attempts using slower burning powders, and even with the lowest pressure loads I still got leading and poor performance. I thought let’s just throw all caution to the wind and roll with it.

14grs of Green Dot- the famous Cast Boolit Group Buy mold the “Chargar 311407”, air cooled wheel weight alloy and Bull Shop “Speed Green” lube. Sized to .310 with Checkmaker™ 30 cal gas checks of .010 copper. These formed checks were by all outwardly appearances… definitely guilty of being “miniature bottle caps”.

Was this load to be a barn burner? A DRT (dead right there) Moose hunt cartridge load? No obviously not. I just wanted to get on paper without embarrassment using my beloved Ruger #1 and my own self manufactured gas checks.

Test rounds here loaded up the belted monsters and Green Dot, and a mild LEE factory crimp:

I set up this first target at @50 behind the house, and I bout’ fell out of my chair when my 5 shot group was done and touched just like copper does out of the old Number 1 @100, with .502 inches center to center as the widest dimension.

My self manufactured- little jagged edge “bottle caps” did their job well. They sealed the bore and prevented leading shown by subsequent load development.

I knew from that point on I was on to something, and all the work it took to create my Checkmaker™ dies was well worth it.

What my goal has been, and what I set these dies up to do is create a gas check that gives you a wide choice of metal material types and thickness to work with- fit a wide range of boolit shanks with an absolute minimum material waste, all within one caliber.

A set of affordable dies that has few parts and heavy duty, but produce accurate concentric gas checks with your reloading press, that meet or exceed the performance of “Factory Manufactured” gas checks.

That includes the little “miniature bottle cap”, because what that bottle cap does is allow thin metals to work. Work for a guy who wants to use beer cans at no cost for gas checks. Work for copper and the metals you can get inexpensively. Are you going to out shoot factory checks with beer cans? Well maybe not but at least you have the option to choose and experiment with what may or may not work out so well for one of your firearms, but may be very acceptable for another.

To further explain my design… and I think I may have unsuccessfully attempted to do so trying to explain to the gentleman who (thought bottle caps just didn’t look right) sent the email, is when you use thicker metal material to form checks, the “bottle cap” disappears, and your gas checks start looking like factory made checks.

Starting with .014 in the 30 caliber, the checks formed start looking more familiar. Plus you have the machine already in place- your single stage reloading press that is fully capable of cutting and forming thicker materials.

The Checkmaker™ accuracy reports showing from seasoned cast shooters is remarkable. Groups are meeting, exceeding and surpassing factory checks.

More from Ben:

Here is a good example of Patrick L and some of his first loads using his 30 cal Checkmaker™ and lever action rifle with beverage can gas checks:

Then he finished later with .011 AL @ 100 yards and his 30’06:

Some folks are using super glue to glue on their poorly fitting home made gas checks from another brand of dies.

Shown here are photos from our memeber “Hud” Roger of his boolits retrieved that were checked with his own 30 caliber Checkmaker™ manufactured gas checks and .005 beverage can aluminum and NO super glue.

The gas checks hung on for the entire ride dead solid and refused to let go.

I’m proud of my accomplishment in bringing these dies to market for cast shooters, and I’m very happy the design has been proven sound.

Instead of seeing how fast one can make a pile of pretty little cupped gas checks, my focus has been on fit and accuracy results by actual shooting performance.

I’ve found as others have- manufacturing your own gas checks becomes a natural part of the reloading process. It is fun, and Checkmaker™ dies will have you forming a pile of quality gas checks in short order. Much less time than case prep and other tasks.

My goal is to support and offer dies in all calibers- a complete line of Checkmaker™ dies including PB “Plain Base” check forming dies for your favorite plain base molds as well.

Patmarlins is happy to provide a die set that will give the end user a wide range of choices within one caliber, and allow him [or her] the ability to manufacture their own gas checks, eliminate waste, and eliminate the need to buy factory checks if so desired all with the accuracy of their single stage reloading press.

All dies come with a “No BS” satisfaction warranty and are guaranteed to work spot on flawlessly, or your money back.

You can cut extremely close quickly, and have every little material waste:

Here’s a sample of targets from Checkmaker™ users…

Some great shooting from our CB member .30/30 Guy- Robert:

More shooting from CB member and craftsman Ben:

More from Patrick L: