May be a dumb question but I have to ask . What could cause the mouth of my once fired cases to have a larger diameter than they used to from the same rifle . I'm not a reloader so I didn't know what could be going on so I found an old box of spent brass from the same rifle and they for sure have smaller diameter case mouths . I cant hardly insert the bullet form an unfired round into an older case but on the more recent ones I can easily insert the bullet loosely . Is something out of spec with my rifles' chamber ? Thanks