This deer season my son and I came upon a chambering problem. One was with .270 and the other was with .30-06. I pretty much shoot handloads, although these two calibers usually use up much less than a box each, during the season. I'll admit that I "scrounge" for spent brass at the local range. I tumble, full length resize with RCBS dies, trim for case length and reload; been doing this for years. Problem is that for both calibers, a few rounds will chamber, the bolt closes fully, but the action won't rotate into cocked and locked position. The rounds will extract with normal effort and there are no markings on either the bullet or case. Of course, both case length and overall length check out below the max, with a dial caliper.
I've been told that brass fired in actions other than mine may have fire formed the body of the cases to a size larger than my chamber. Apparently full length resizing only affects the neck and shoulder of the case, not the entire body of the case. I had a similar problem with a new S&W M&P 15 and the solution was to use "small base dies". Haven't had a problem with that gun since. My Mini-14 will happily digest my reloads, but the S&W will not, unless I use the small base dies.
This may be a solution for cases that haven't been processed, but I have literally hundreds of these calibers reloaded already. The same gunsmith told me that his advice would be to safely chamber every loaded round and discard any that won't allow the action to close; pull the bullets and recycle them and the powder and toss the brass. Then he said what he does is to tumble, resize and trim found brass. Then he chambers each one, discarding any that are "tight". He then reloads and again checks for proper chambering before boxing them up.
Reliability is a big issue and in my situation this seems to be a solution. I'm also considering "small base dies" in these calibers, but I am a little fuzzy on whether or not they completely resize the entire case. One other thing. My handloads function flawlessly in two military actions I have; a Springfield 03-A3 and a Garand. My understanding is that military chambers spec a little "loose", which could lend some credence to the idea that brass fire formed in another gun might not work in my hunting bolt actions. Any ideas would be appreciated.