I have recently reloaded some 260 Rem. and things have gone ok, but now on my second reloads when I started seating some bullets I found it was difficult.

It was definitely harder than it was before so I stopped after say six rounds. I took some resized brass and with my calipers checked the dimension on the outside of the neck and they were running at .291 to .291.5. So I subtracted .030 for the thickness of the brass and got .261 to .261.5. Knowing the bullets were .264 actually when I measured they were .264.5.

I remember checking the first reloads and I believe the dimensions were .292 to .293 on the outside and .030 less .262 & .263 inside and they felt just about right in my opinion when I was seating the bullets.

I'm wondering if there is a standard of sorts to go buy?