CCI CB Long 0038 is for 22LR guns, if you have a bolt action no worries about feeding, if you have a standard 22LR off the shelf will most likely not feed, if you upgrade the cocking hammer and spring, rod with say a KIDD setup that has a Subsonic spring in the kit (from my experience) it works just fine. If you have a auto pistol, they work great, if you have a custom build 22LR (polished bolt, receiver, etc..) they have worked fine for me.