You can polish and then ream if needed but you can't go backwards. If you can chamber a cartridge it isn't short chambered. Short is far to short to even approach with a cartridge. Once you see one you know what it's like. It's not just a little. This ones starting to sound like a put together by amatures. I have had a few come by that were simply too tight to chamber everything fed to them, that was factory ammo...so a gentle touch with a reamer took out just powder but solved the issues completely. Then a polishing...