Originally Posted by Mikecr
I don't bump cases until they need it. Sounds like yours don't.
You're not thinking about what you're doing.
You said to begin that you wanted to bump cases 1thou. Well you're not suppose to bump from just any ole number, but from chamber fit. And you can't do this until your actually get there(fully fireformed).
When you sized them all from 2.1225 to 2.1115, you departed from your goal of 1thou straight to 11thou! You're also straying from "trying not to work the brass that much" which is causing a mess & it will only get worse pretty fast.
the factory ammo i fired all measured a consistant 2.1225. so while this might not be fully expanded to the chamber, i figured its a good place to bump them from, and back .001, rather than full length size them back .011 (why go all that way back if i dont need to)
the few that i did size to 2.1115. were not the bulk of the cases, they were a few that went past 2.1215 when i was setting up the die , so they became full length sized to keep them all the same. and were used for fouling only.
the full length sized cases (about 5) grew after firing from 2.1115 to 2.1200 consistantly.
the cases i bumped to 2.1215 ended up from .0005 to .0200 smaller. they were different charges so i dont mind them being in-consistant. but however they didnt expand to my starting size, or even grow past it. except one case which had pressure signs on the case head.
so now my theory is. the factory superformance ammo, must have quite some pressure behind it, and the rounds i loaded didnt have as much, except the one with pressure signs.
so i should have just started by full length sizing everything, even though i have a reliable chamber sized piece of brass to bump back from.