Carlson's Snap Caps allow for safe release of firing pin springs. A spring loaded striking area cushions and protects firing pins (centerfire calibers only). These Snap Caps are an excellent tool for teaching and eliminating flinching.FeaturesPrevents damage and prolongs main spring life.Precision machined to true SAAMI specs.Primer material is correct hardness to prevent striker/firing pin over-protrusion.Aluminum won't damage the chamber/extractor/ejector