When seating bullets with both Remington and Norma Brass I'm finding the Case expands just below the shoulder making the rounds hard to chamber. I suspect my RCBS seating Die has a expander ball that is .001 to .002 undersize. I will call RCBS on this next week. My Gunsmith made me a size die to bring this back to spec on a loaded case. It just touches the shoulder area of the case and allows the rounds to chamber freely. Has anyone else experienced this problem?

It sounds to me like you may be letting the roll crimp function of the seating die touch your cases a bit. If you screw the seating die in too far the roll crimp will expand the case in the shoulder area.

Raise your die a bit and adjust the seater stem down further to see if this is indeed the problem.

If it is, don't feel to bad about it. I've done it before on accident.

Have a good one,

Reloader

To find the crimp point just back the die out about 1/2" and with the case in the shell holder raise the ram to its highest point. With the ram in the top position screw the die down till you fell it contact the crimp point. Back the die out about 1/2 turn and lock it. To test the setting measure the mouth of a size case with mics. and run it into the seater without a bullet. If the mouth is the same size you are below the crimp and set to seat.

The problem exist without crimping. It happens when the Bullet is seated?

The expander ball should only be 2/1000" smaller than bullet size. If the case goes to far into the seater when you are seating it will try to crimp at the same time.

I measured my Expander Ball @ .305 and called RCBS. They said it should be .307 and a new one is on the way.