When storing your shotguns, let off the tension on your cocking springs. This practice not only adds to the functional life of the shotgun, but keeps it in optimal working order. The Pro-Shot 20 Gauge Snap Caps feature spring-loaded firing pins for the ease of tension that is released when your shotgun is fired. Each brass snap cap includes a cotton mop loaded in natural lanolin that fits into the chamber, providing a barrier against rusting.