Just swap this drop in conversion with the bolt carrier group from your5.56/.223 chambered rifle and you will be ready to shoot .22LR. Ships with 25rd 22LR magazine. Compatible withleft handed 5.56mm/.223 chambered upper receiver groups. Ships with 25rd 22LR magazine. For best performance use a round style hammer as notched hammers can cause function issues and 36 grain plated nose bullets have proven to be the best choice for function.**Since .223 WYLDE is NOT a mil-spec chamber, we cannot guarantee fit or function with our 22LR conversion kits**