Last weekend I reloaded a couple hundred .44mags and I would say on about 8 of them the wall of the case wrinkled when I seated the bullet and crimped. I had a pretty generous flare where I could get a decent amount of the bullet started in the case. I am using Berry's plates 240gr flat point bullets so I am running a very very light crimp. I am only loading these to 1200FPS so I shouldn't need a super heavy crimp.

Any thoughts? Is this pretty normal with long straight walled pistol cases? I had this problem on .357 mag but when I increased the flare it seemed to do the trick. That same amount of flare doesn't seem to be working here. I don't want to go too extreme with the flare because of the light crimp (heavy crimp will cut through the plating and cause it to separate).

Dies are RCBS.