inconsistent F/L sizing

[jdefranc938]

I'm attempting to get 1,000 rounds prepped and ready for a PD hunt and I came across a problem. I had purchased some Hornady once fired brass from someone and am F/L resizing it now. Approx 1/15 will not cycle in my Cooper (bolt will not lock down without a TON of force). I haven't tried any of the brass in my CZ yet. I have not had this issue with other fired brass from my Cooper (not that I would expect to have the issue since it was from the same chamber). I tried adjusting the RCBS die to bump down the shoulder a bit more but it really didn't effect anything. When I found one of the brass that wouldn't cycle, I lubed it up and ran it through the same die again. When I tried to cycle it this time it was fine. So, where lays my problem? I really don't want to have to run all of these sized brass through the rifles just to see if they feed, and I really can't adjust my die down anymore because the press is already "camming-over" pretty hard.

Thanks in advance,
Jeff

[Joe O]

Since your FL sizing is already caming over in your press,the only suggestions I would try is a thinner shell holder,or a small base die,but first I would use a bump shoulder gauge (Sinclair),to measure before and after sizing,plus check the cases that have been fired in the Cooper.Most custom and semi custom guns have a chamber cut closer than SAMMI specs.

[jdefranc938]

Ok, here's what I am gettin confused on though. I took one of the pieces of brass that was fired out of the CZ and tried to cycle it in the Cooper. Wouldn't fit (Big surprise). So I played with the sizer die until it did fit. So technically, shouldn't all brass fit then once sized in that die? And why is it that If I run it through twice, it will cycle?

[jdefranc938]

Well, I switched to a Redding die and so far, I haven't had a problem. Maybe it's just a coincidence though. I'm going to call RCBS in the morning and see if they can offer me a reason/replacement to why this happened.

[OldTurtle]

It may have to do with the type of press you are using (you didn't say).. some of the older "C" type presses would distort more, under pressure, than the "O" type... I have an older Pacific "C" type that I replaced with a Forster and my brass is coming out much more consistent than it used to...