I neck size for my .223, .243 and 7-30 Thompsons, as well as other non-Thompson calibers.
For the .223 I never seem to have a problem with the shoulder "growing" and so, I just don't have to full size that caliber's brass. (Even though they are loaded to a max powder load).
However, for the 2 other loads I find that after neck sizing, and before loading, I pop each piece of brass into the barrel to make sure the brass will seat properly in the barrel. Now, to some that may seem like an unecessary step, but I can assure you it doesn't take all that long, and for the surety of the load it's worth the time. For those pieces of brass that don't "make the cut" here, I run those thru a Redding Body size only die. That die simply bumps the shoulder back to where it should be and the brass then fits in the chamber like it should. Also, the body size only die doesn't re-work the neck again.
These procedures have given me some very accurate and consistent loads, and brass that chambers every time.
I believe the little .223 brass seems to have enough staying power that the load doesn't cause the shoulder to move. The larger loads have enough ump to make the brass move and stay after a few shots.
Dave