I couldn't chamber 30-06
I trouble shot (troubleshooted?) everything I knew how to. Gauged, calipered everything.....
I got a LOT of great suggestions and ways to check them on the forum here. And I diligently checked everything.
One suggestion that was especially useful was to use a marker to black the cartridge and try to chamber it to determine where the problem was. It did show a problem with the shoulder angle.
Someone suggested I examine my dies. There was ring of lead inside one that apparently changed the shoulder angle because everything else checked out perfectly.
No idea how it got there, but my problem, that I had been working on and off for a couple of years, went away.
That was a real Reloading Forum victory.