Gas Check

Copper-alloy cups affixed to the bases of specially designed cast bullets with the intention of reducing deformation of the base under high heat and pressure and thus reducing leading. A gas check is a device used in some types of firearms ammunition. Gas checks are used when non-jacketed bullets are used in high pressure cartridges, to prevent the buildup of lead in the barrel and aid in accuracy.

Gas Check Bullet
Cast bullets as cast (left), with gas check (center) and lubricated (right)