Do-it-yourself gas checks
What are gas checks?
Gas checks are used for non-jacketed bullets that have moderately high pressure loads. The purpose of gas checks is to prevent high-pressure gases from eroding the bullet, thus preventing lead from being deposited in the barrel. Gas checks also tend to scrub the barrel clean by picking up lead deposits and carrying the debris out with the bullet.
Gas checks look like tiny metal cups [a] with a wall less than 0.10 inch high and an outside diameter slightly larger than the barrel's groove diameter. Gas checks are made with malleable sheet metal stock such as copper, zinc, aluminum, bronze or brass. Bullets must have a reduced diameter at the base to allow gas checks to be fitted.
What are FreeChex™ tools?
FreeChex tools are used to fabricate homemade gas checks for a fraction of the cost of those from commercial sources. The original version [b] is no longer sold.
FreeChex II [c] is capable of shearing thick metal stock up to 0.022 inches thick. Metal stock is placed in the slot of the anvil [d] and then the cutter-guide [e] is inserted in the anvil (on top of the metal stock). [f] The cutter-guide is then given a rap with the mallet to shear the metal. The mandrel [g] is then placed in the cutter-guide and struck with a mallet to form the gas check. [h].
FreeChex III [i] tools are capable of making gas checks with a single stroke by using a hand-operated press such as an arbor press. Metal stock is cut with a shearing/forming tube [j] that cuts and forms the gas check. A spring is used to re-set the system.