Thread: Why does pulling case out of FL resizing die require so much force?

I have a set of RCBS dies in .222 Rem, they were shocking to use, in the pressure-to-operate department, and tore a few rims (rimless) off the bottom, on the up-stroke. I tried everything with them, and eventually discovered a' breather-hole', in the die-body, was blocked with swarf. I sorted this and put a cross file-groove ,across the locking-ring (corresponding to the hole, which it covered). I still cant get my head around Why it worked, but it did . I've also never checked my other dies to see if they have this hole, but cant recall noticing one