41 Caliber Crimp on Gas Checks for .401"-.410" Bullets .379" Diameter Shank Bag of 1000

41 Caliber Crimp on Gas Checks for 40 & 41 caliber bullet molds and others measuring .379" on the shank. Many custom mold makers are designing their molds for this gas check. If you cast your own bullets, these crimp-on gas checks will enhance their performance. During sizing, gas check crimps to the base of cast lead bullets to seal gasses and protect the base from deformation.