Shoulder set-back .30 Luger
 

I had always loaded bullets with a cannelure, roll-crimping as the final step.
I just loaded some 90gr. XTPs with no cannelure, and an ejected live round showed the shoulder had collapsed; is lack of crimp creating excessive case OAL, and the case mouth is being jammed against the end of the chamber?
It's possible the case is slightly long, as I did not measure any after the last shooting/loading, and that, combined with no crimp?

Perhaps the case needs full length sizing dies? Does the brass need trimming after the first resizing? If the brass was properly sized, is there dirt in the Luger's chamber?

Crimp should not normally change OAL unless the die is set to push down too far.

Measure OAL, and Mouth to Case Head distance on reloaded cartridges. I have a standardized chamber gauge tool for testing every cartridge I reload.

I've trimmed cases before, but may have a case or thirty that's been reloaded three times since trimming.
I'm in no hurry, so will measure OAL after the next sizing.

I have been loading 30 Luger brass for many, many years, and have never found a need to trim any of my brass. Some of my brass has been reloaded 10-15 times, or more. Something else is wrong in my way of thinking. Are you getting bullet setback?

Plus one.

I have also been reloading .30 Luger for about 50 years and while the short neck is not ideal, it's still not hard to do.

IF your bullet diameter is too large, trying to seat it in a neck that is too tight may cause the shoulder to collapse. The answer is to either bevel or expand the case mouth to start the bullet.

Neck tension is critical to prevent bullet setback as the cartridges feed into the chamber. Depending upon the bullet used, a crimp may be - and often is - necessary.

WRT trimming the cases, I almost never do as I've found it to be unnecessary.

Thanks for the replies.
I'd never had an issue before trying the 90gr XTP, which appears identical to the 85, except for length, so I didn't have to adjust seating depth, the diameter is the same as the 85s; the only difference, externally, is lack of roll crimp with the 90s.
I have to feed the .311" 85s through a sizer, and was hoping to skip that step by using the 90s, but the 85s have worked for years, so, as dad used to say, "DFTP"; don't fight the problem.