Thread: Dented case mouths

Can anyone shed some light on what might be causing the case mouths on my .223 cases to have a dent/flat spot on them? Two are brand new hornady factory rounds and other three are once reloaded federal. Have always fl sized but picked up a collet die the other day which is when I noticed the problem because it doesn't remove them like a fl die does. Haven't shot this barrel much so haven't taken a lot of time looking at cases as mostly factory ammo. I could understand if it was a semi as they can be a bit more violent ejecting but it's a bolt action. The federal aren't quite as bad as the hornady and geco even less but that I put down to different case hardness.