Gifters wrote:So... speaking of dangerous loading practices and not wanting to start a new thread or search back beyond, I figure Hoot will probably read this and offer insight. Shot just a few rounds before packing everything up for deer camp tomorrow. Only 2 of my hand loads that were .4990 for case head while the One round of the factory Hornady Black measured .5030 . I'm dumbfounded, that seems really over presure since it was a new round (possibly thin case walls at the head?) but yeah that case needs to get tossed! anybody else experience factory ammo that bad. BTW I had one factory Hornady round pushing 2475 out of the chrono... I'm guessing it was that one.
Loads with starch in their undies are not the only cause of excessive
Case
Head
Growth. My first 450b (Bushmaster) had a loosey goosey chamber. It was great for feeding just about anything reliably but even mild loads sustained more CHG than anyone else on the forum was experiencing for the same recipe. If that wasn't bad enough, the looseness also allowed the cases to shrink in length quite a bit for the first 2-3 firings before they settled down. It was not unusual to see them go from 1.697 new to 1.679! I've read here of other members having experience occasional excessive CHG with factory loads. Like you, they were at a loss as to why. Your guess of thin wall is as good as any. Hardness can also be a contributing factor. Starline brass is thinner walled than Hornady but they are a harder brass alloy and as such, don't sustain any greater CHG than the Hornady brass do. If anything, they sustain a little less per firing. If after resizing, you can still get them to pass the "Thunk Test" keep using them. As soon as they stop falling all the way in without needing help, toss them. The only thing worse than having to stop on the firing line to tap out a spent case with a cleaning rod, is to have a failure to feed far enough to lock the action while needing a followup shot when hunting. Mass production manufacturing will allow occasional cases that fall outside of some spec to sneak through. If the other factory loads from that box do not do the same thing, you just write it off to bum luck and add the bad ones to the recycling box. Some scrap metal recyclers will take deprimed cartridge brass and some won't. A rare few will take them with the spent primers still in them.
I always set aside a handful of new brass, that are the same length, to make up my hunting loads from. Its a lot cheaper than the cost of the hunting trip.
Hoot