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Originally Posted by Swifty Morgan
If I understand SAAMI's material, the drawing says 0.473" at the mouth. I didn't use a caliper because it seemed like it would be hard to get an accurate measurement on something tapered, and I figured an actual chamber would be the best tool to prove the rounds worked. I didn't consider the possibility that one chamber would be tighter than another.
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It's not just "tight" chambers you need to be concerned with. There's also the question of bullet/cartridge length and freebore, or leade.
In a semi-auto, the cartridge is located (headspaced) in the chamber by the mouth of the case coming to a hard stop against a shoulder at the forward end of the chamber. This means the bullet protrudes into the barrel. We don't want the bullet to engage the rifling before it starts moving, so the first portion of the barrel is reamed to remove the lands, leaving a smooth bore for the bullet to fit into. This is referred to as freebore, or leade.
Different barrel makers may ream to a different length of freebore. For all I know, different reamers with the same factory may produce slightly different lengths of freebore. I have had guns that refused to chamber multiple brands of factory ammunition due to insufficient freebore.
That's a long-winded way of saying that your problem may be due to the crimp, as you surmise, but it could also be that you have a bullet with a "fat" ogive profile and a barrel with a short freebore.