CCI Mini-Mag .22 LR 40 Grain CPRN: Bolt Bounce Reduction in Semi-Automatic Rimfire Systems Bolt bounce occurs when the bolt rebounds after closing, potentially affecting ignition timing and chamber stability. CCI Mini-Mag .22 LR 40 Grain CPRN generates sufficient cycling energy to minimize incomplete bolt closure events in most blowback systems. Stable bolt closure improves firi... https://bulkammotogo.com/product/22-lr-40-gr-cprn-cci-mini-mag-0030-5000-rounds/