The purpose of the crimp is to hold the boolit in place in the case during the chambering sequence and recoil of the firearm.
Revolvers differ from semi-auto in that a revolver tends to pull a bullet out of the case during recoil while a semi-auto tends to push the bullet into the case during the feed cycle. Hence the need for different crimps.
A few years ago, I purchased some Federal brand 9mm rounds that had aluminum cases. I was testing some magazines for feeding issues and used the same cartridges repeatedly without firing them. I found that after running them through the feed cycle 3-5 times, the overall length had changed significantly. In some cases, up to .125 inches. Always shorter than they were originally. This can cause significant pressure problems.
I found that I could actually move the bullets in the case with just hand pressure.
The brass cased ammo from the same manufacturer didn't have that issue.
I will never buy another round of aluminum cased ammunition.

All this being said, if the crimp is not applied correctly, you may have more problems than just a chambering issue.
It sounds like you have figured your issues out.