Recently I started loading some .223, I was about out, using Xtreme 55gr. FMJ. A couple weeks ago I had a round get stuck in the chamber of my Palmetto State Armory upper. I chalked that up to no biggie, a fluke.
So after that I have continued to load more .223. I was running them through the Lyman cartridge gauge for a plunk test. They seemed to be fine. I decided to drop some into the PSA chamber since that is where I was having the problem. I still had some that were sticking. hmmm. So I started doing lots of a measuring with my caliper. What I finally found was that some cases were about .002 larger about .25" up from the base.
These cases were sized on a Hornady single stage press using a Hornady sizing die that has been used many, many times before with no issues. So I took the remaining batch of cases I was using and dumped into a 1 gallon Ziploc and sprayed the Hornady case lube, love that stuff, into the bag and relubed the brass. Then I put the sizing die, same die as in single stage press, into the Hornady AP that I am using and basically did the sizing again. There wasn't much resistance from the bass going into the die but guess what. All of those completed cartridges fit into the PSA chamber just fine.
So what was learned during this process? The first thing is the chamber in the PSA upper is ever so slightly tight. I did have a couple cartridges that would not plunk in the PSA upper but would in my M&P upper. Granted the M&P does have a lot of rounds through and the PSA only has a couple hundred.
And the most important thing learned. Operator error. During the first sizing operation I, apparently, did not have the die adjusted as well as it should have been or was not getting a good full cycle with the ram on some cases. The other thing is I should have stopped sooner during this loading process and taken more time to figure out what the problem was.
Hopefully I got that typed out so it makes sense. So there it is! Live and learn.
Edit: I did do one other test during trying to figure out the issue. I don't remember where I read it but I took a black Sharpie and "painted" the bottom part of 1 cartridge that was being a problem and put that case in the chamber of the PSA upper. Sure enough it left a couple little marks where the black had been scraped off.