I am going to post the reply I got from RCBS when I inquired about remedies:
CUSTOM SEATER PLUGS
RCBS realizes that one plug can not be made to fit all the different profile of bullets available. For this reason, the Special Order shop will custom build a plug to fit the profile of the...
Rick: I removed the seating stem and it looked OK, no burrs or irregularities.
I was able to seat, during the same session, a 140 gr. Partition bullet with the same brass just fine. It seems the ogive of the 140 gr. BalTip fits the inside of the seater stem too tightly, and won't release the...
I cannot get a 140 gr. .284 Bal. Tip bullet to seat in new Win. 7mm-08 brass. More specifically, the bullet sticks in the seater die. I use the RCBS Rock chucker press with RCBS dies. I have never had this happen before. I use motor mica to lube the inside case necks before I size the necks...