I have a 22-250 that I can't neck size with. The only way my bolt will close right is if I full lenght size. I full lenght size with my big game hunting rifles, and neck size with my vermin guns. All my other varmint rifles allow me to neck size. I decided a long time ago that I'd just shoot the barrel out and put a new one on. That was 10years ago.
I always take this gun on my trips, but I don't usually put more than 400 rds through it.
This is gettin a bit long winded. Anyway... I'm not fishin today, so I threw a bunch of brass from this gun in the tumbler, and I know I'm going to have to trim every one of them.
I've been on this sight for a couple of months now and There's alot of good dope on here. You can just sit back and read and usually someone else has already asked whatever you have on your mind. Great tool!
Thanks Dave

Is the brass your trying to neck size been previously shot only in your gun and if so, what is the length of the cases (meaning is it due to be trimmed)?

Might want to check that the chamber's in line with the bore.