Failure to feed on some handloads.

[Big Smoke]

Here's a dilemma for you techie types. On some of my handloads, for .45 acp, I occasionally get problems with feeding. So I broke out the dial calipers and case gauge and did some checking. All the cartridges are the same, with the exception that most of the problems are with lead bullets, but not all. Some are FMJ. OAL is in check. No problems there. Case length is check as well. I checked the case diameter, and it's fine. I checked the crimp, and it's fine.
Everything is within spec. But some of the cartridges will check in the case gauge, and some stick about half way in.
I can do a drop test in the barrel, and they will load fine, but sometimes out of the magazine it will not load all the way. These are the ones that have a problem in the case gauge.
I've come to the conclusion that the problem is with the brass. Probably a nick or something that I'm not seeing. But I'm I overlooking something? I'm kind of at a loss.