Originally Posted by boomtube
"...I have reloaded Federal brass in 243, FL sizing, up to 8 times ...."
Flat primers and incipent head seperations are effects of exccesive effective headspace caused by too much shoulder set back in FL resizing, not excessive pressure as such. "Flat" primers really don't tell anyone much about presure but expanding primer pockets sure do. 'Saving' significantly over-loaded cases with stretched pockets by using a pocket reforming tool doesn't appeal to me.
Federal cases are great for long life with normal pressures because it is a bit soft and therefore can withstand the effects of more reloading cycles before it work hardens enough to split but Fed can't take excessive pressure as long as harder cases can. I like long life and feel no need to push the pressure limits so Fereral cases work great for me. You decide what you prefer and live with the downside.
I doubt anyone thinks the OP is still checking here, these new responses are aimed at current drop-in reloaders having the same problem.
I can believe what you're saying about the the signs of and actual case seperations I've been experiencing have something to do with excessive headspace. Its almost as if they're being stretched and that's the weakest point. Interestingly this only seems to happen with heavier freight - the 100 gr bullets even when not loaded to max charges - and not with 85 gr bullets loaded, even when loaded to max listed charges.
Now, how am I creating excessive headspace by bumping the shoulder too far back? I am doing FL sizing with the ram coming up into full contact and overcaming a bit. So the shoulder is set by the sizing die, which I assume is to SAMMI spec for the cartridge. I suppose the only way is to back the die out a hair so that the ram doesn't touch the base of the sizing die. Is this correct?
I'm with you on running medium velocities if they result in better accuracy and that's what I normally shoot at the range. But I have a few good max or near max suggested loads that I want to use for hunting though if I can't get around these incipient case rupture issues on this one I'll just have to back off. One of them is this 100gr BTSP 43.3 gr IMR 4831 that goes out at about 3050 fps and is an accurate node. It has produced some tight groups on 2 outings (3 of 4 in .25", 1 flier .7' - 1" away). Yesterday that load was registering 3120 and it was a hot day; kept ammo in the shade but still got higher velocities; I don't understand that. Accuracy varied. There are micro stress lines on most of the cases...a fine line where a future rupture would probably happen. That seems hot for a 243Win. I'd like to use this load for hunting or even long range shooting if its safe and stable. I'm figuring that at these MVs this gun should be good out to about 500 yards on deer.
I also don't think messing with stretched pockets is worth the trouble.