The Hornady 7070 Crimp-On Gas Checks are precision-manufactured components designed for 30 caliber cast bullets to prevent gas cutting and barrel leading at higher velocities.Hornady 7070 Crimp-On Gas Checks30 caliber (.308) diameterSpecifically designed for cast bullets1000 gas checks per boxCrimps securely onto bullet baseEssential for reloaders using cast bullets who want to achieve higher velocities while protecting their barrel from gas cutting and lead fouling. These gas checks ensure consistent performance and extended barrel life.