I am having a couple of kinds of trouble.
I have Full Length RCBS dies and am using Hornady brass with Barnes X 270s and Hornady 235s. (Powder not relevant to problems.)

Let me say I have been reloading for 40 years without problems.

I resize and check for case length less than 2.60 and chamfer the case mouth.
The empty cases chamber just fine.
Then I set bullet seating with cartridge OAL to 3.315 with the 235g Hornadys.
Many of the reloaded cartridges will not chamber.
A number of the case necks are "rolling" back into the case. (I am wondering if I have very soft cases)
With the Barnes-Xs, I don't see the case neck problem, but 4 of 5 loaded cartridges will not chamber. I set bullet seating with cartridge OAL to 3.325 with the 270g Barnes.

Additional comment: Factory loads work perfectly.
Any thoughts?

Bob,
Are you 100% positive your seating die is not crimping?

Try measuring your expanding ball to see if it is undersized. If you are forcing the bullets into the case neck with to much pressure it might cause the case to be distorted.

Back off your seating die a thread or 2 then turn down the seating plug to get your OAL.
I would bet you are over-crimping and bulging out the shoulder. I've done the same thing with 300RUM reloads.

I agree! You die is screwed to far in. Your over crimping and bulging the shoulder. That is why I use the Lee factory crimp die after seating bullets. It don't bulge the necks.

You all were right.
Today I made the adjustments and loaded up 10 rounds. All chamber properly.
Thanks.