Gas Checks Features Lyman Gas Checks come in a wide variety of sizes to accommodate all of the most popular cartridge case calibers from .22 all the way up to .45 caliber. These gas checks come in the form of gilded metal cups that fit into the base of cast bullets in order to protect them from hot powder gases. Not only do these Lyman gas checks protect cast bullets from hot powder gases but they also help to permit a higher velocity. These gas checks are easy to seat during sizing of your bullet cases and they have a crimp-on design. Lyman gas checks come in a package of 1 000 and are available in 10 caliber-specific sizes. Gas Checks Specifications Lyman Gas Checks .22 cal 1000/ct