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Homemade Gas Checks

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Homemade Gas Checks Homemade gas checks. The “Freechex” system. Haven’t loading components gotten expensive? I recall when I began handloading in the early 90’s paying $35.00 for 1/2 kg of powder and the same for 1000 primers. We are rapidly approaching double those prices now. In fairness we are all quick to reminisce about the prices we used to pay but no so quick to remember how much more we earn now. That is to say that whilst prices have gone up I will wager that so have the average handloaders annual earnings. Still, the playing field has changed for me personally and those care free days of the single, unattached man spending his weekends and cash on rabbit shooting are gone and now I have a family to factor into the equation. I surely don’t want me hobby being a burden on the family budget and this in mind I am continually looking for ways to make my shooting dollar go just a bit further. Gas checks are the mainstay of a lot of cast bullet shooting. For those not familiar with them a gas check is a tiny gliding metal cup that is slipped onto a corresponding shank on the base of a cast bullet and serves to add a degree of strength and rigidity to the bullet base. In real terms a gas check protects the base of a bullet from heat and pressure and provides a stronger gas seal than is possible with lead alloy alone. Commercial gas checks from Hornady are manufactured in such a manner than when a cast bullet is run through an appropriate sizing die the check crimps onto the bullet in a very positive fashion. The older style brass gas checks from the Lyman company are strictly ‘slip on’ and do not crimp in place when sized. Both work as they should and are fine, quality products however the last box of 1000 Hornady .30cal gas checks I bought were $55.00 and that was quite some time ago. Since that time the cost of all metals has gone sky high and this is having a roll on effect on all facets of life including our shooting sport. So what is the solution? How about making your own? Freechex™ for the USA. I have been experimenting with a pair gas check making devices for .303 and .224 calibres. Charles (Charlie) Darnall from Camarillo, California supplies a gas check kit that he makes and sells exclusively on Ebay. “Freechex™” is his trademarked brand name and a search on www.ebay.com will locate his auctions. The gas check making kits consist of three components; a punch for cutting discs of check material, a forming anvil and a mandrel inserted into the anvil. A very simple and easy to use system built to fine tolerances and capable of producing perfect checks. It all sounds too easy and good to be true but from first hand knowledge I can attest to the effectiveness of this gadget. Here is how is all works. Each kit is supplied with a hollow punch to cut discs of the chosen gas check material. In the case of .30cal (.303) Charlie reams his kits to suit a 3/8 inch (9.5mm) wad punch. Disc of 3/8 inch form .30cal gas checks of the correct dimensions to fit most, if not all, .30-.31cal moulds. Using the punch supplied and a piece of end grain timber or a slab of lead to cut on, the material is punched out and discs collected. The discs are then inserted into the forming ‘anvil’ where they slide to the bottom of the die and stop at the shoulder where the die tapers to the end diameter of the check. Next the forming mandrel is inserted into the ‘anvil’ and with a couple of gentle taps with a soft face hammer on the mandrel, a gas check is formed and pushed from the bottom of the ‘anvil’. It’s that simple. I have found it is best to use at least two gentle strikes of the hammer. The first blow begins the forming and the second completes. When using one solid strike only lop sided checks are frequently formed which is not desirable as they potentially generate an out of balance bullet with an imbalance of weight. Recently Charlie has been refining his design and added a nice little innovation. Freechex™ II has a fine cut is made horizontally through the forming die/anvil in such a way that a strip of check material can be inserted. A hollow cutting punch is then put into the die/anvil and tapped with a hammer to cut the material. The freshly cut disc slides to the bottom of the die with the hole punch through which is inserted the forming mandrel and with a couple of taps a gas check is formed. This new system is much faster to use and due to the tighter tolerances of the cutting punch and forming mandrel makes a better quality product also. Charlie will taylor Freechex™ and Freechex™ II sets to the buyer’s requirements for bullet shank fit (dictated by the forming mandrel) and end gas check outside diameter (anvil exit size). Both anvil and mandrel are expertly hardened however I was able to hone my anvil out from the supplied .311 to .315 with the aid of some 600 grit wet and dry paper and a piece of 7mm brass rod. This process did take some time which is testimony to how hard the components are. The additional honing I performed created a very smooth finish that can be felt when forming the gas checks as the material slides through the anvil with a great deal more ease. Gas check materials. Traditional gas check material is gilding metal; the same alloy used in bullet jackets and this is certainly the case with Hornady commercial gas checks. Gilding metal is an nominal alloy of copper (Cu) (90-95%) and zinc (Zn) (5-10%) and is technically a form of brass. Lyman gas checks appear to be traditional brass as they have a bright gold colour instead of the copper appearance of their gilding cousins. Commercial brass and copper are materials very suitable for making home made gas checks however I want to use these as a last resort due to the price of each metal. Available as ‘shim stock’ both materials work as they are expected to however they are not the only materials that will make quality gas checks cost not withstanding. Aluminium (Al.) has long been touted by backyard gas check makers as a suitable material and most often the source of this metal is quoted as beverage (soda) cans. The major benefits in using Al. are 1) it is soft and easy to cut/work and 2) beverage can material is FREE. All that glitters is not gold however and the one drawback I have found with beverage cans is the mainstream varieties (Coke, beer) have wall thicknesses of only 0.0042 inch or just shy of 0.11mm. This is very thin indeed especially when you consider that Hornady .30cal gas checks are made from 0.017 inch/0.43mm material. Four layers of beverage can Al. is required to make a check of equivalent gauge. Our cousins in the USA have it a little better as their beverage cans appear to be 0.006 inch in the side walls giving them a 50% advantage. That said this scrap metal still has its place and can be of use. Al. in heavier gauges than beverage cans is most suitable though. One good source of heavier gauge Al. plate is lithograph printing plates used wild in the printing industry. I have been able to locate such plate measuring 0.30mm/0.0118 inch and this is very suitable material. Bullet mould gas check shank variations. Bullet gas check shanks generally taper slightly from bottom to top to aid in the application of the gas check. The taper is as little as 0.004 inch. The major variation to be aware of is the shank dimensions from one manufacturer to another. Lyman .30cal moulds bare shanks of 0.280-0.285 however Jim Alison of Cast Bullet Engineering (CBE) in Australia tailors his mould shanks to best suit the intended use. Jim has a huge range of bullets for the .303 British and due to the wide variations in groove measurements in the good old ‘three oh three’ he cuts some gas check shanks larger than the norm. I find Hornady commercial gas checks must be flared slightly prior to fitting to a CBE shank but by cutting shanks 0.286/0.290 Jim helps ‘bump’ the gas check out in diameter to better fill ‘stout’ barrels. This is a good feature and promotes nice parallel driving bands and straight bullets especially beneficial during the seating process. Bullet designation Shank base Shank top CBE 316 175 0.286 0.290 CBE 316 240 0.286 0.290 CBE 313 215 0.284 0.289 CBE 313 220 0.284 0.289 Lyman 311466 0.282 0.285 Lyman 311316 0.280 0.285 Lyman 225415 0.214 0.214 Lyman 225462 0.210 0.213 The exception to the taper design I discovered was my Lyman 225415 flat nose bullet; a proven accurate and effective small game bullet. Its shank is a parallel 0.214 but both Lyman and Hornady .22 checks fit it with ease. DIY gas checks – trials and tribulations.
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