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How are you measuring for shoulder bump? You cant really measure bump correctly without a hornady kit which attaches to one blade of your caliper and uses a specific bushing to measure off the shoulder to compare cases. You simply can not eyeball it.
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Remeasured the firing pin protrusion,it's a little over the spec. that Steve @ Shooters Supply gave me.(.055 vs. .069)I compared new full length resized brass to one time fired brass (same lot of Winchester brass)found very minor case body length difference.Notes outside in shop,measured w/digital caliper. If the headspace were off by much I'd have a noticeable differance in base to shoulder length.If memory serves the measured differance was .007 to.010,new F/L sized vs. fired. Can't prove it but I'm starting to get a gut feeling about the primers.I haven't had any problems with them before,but there's always a 1st. time. I've had this batch a while,they're Rem.9 1/2.They have been stored the same as the rest of my stock,several brands&batchs.Some older than these by 2 yrs.,and I'm still thinking about the bind on the bbl. nut I found when I bedded the stock. Guess I'll find out next range session.I'm in S.C., we've been having ice/snow/freezing rain. It's supposed to be over now ,so look out range here I come. Let ya' know how it turns out,THANKS all,Paul
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Believe prob. is headspace. Shot today,had 3 misfires. Took 2 and w/ a pair/pliers and pulled the bullets out slightly, approx. 1mm. Before I pulled the bullets out I painted the bullet/case junction w/a sharpie so I could see the movement.Tried to fire them a 2nd time. The impact o0f the pin reset the bullets to the orig. O.A.L. I'm going to load a few more at a lower pressure and seat the bullet touching the rifling.There shouldn't be any slack movement,headspace prob. or not. At this point unless I have a bad f-pin spring the prob. is not the in the bolt. I don't believe the spring is the prob.,I can't see the pin impact changing that much nomatter where the ctg. happens to wind up with the bolt closed. Increasing the O.A.L. will position the ctg against the bolt face,and I plan to use a Lee crimp die to make sure it can't move when the f-pin impacts. F.Y.I. all tests have used the same batch of Rem. 9 & 1/2 primers. Thinking about that I'm going to load a few of the previously misfired cases w/CCI l.rifle primers just to be absolutely sure no primer prob. exists. Thinking about it I used my RCBS case checker to ck. for case streaching ,looking for the thin ring ahead of the the cases belt . The cases I ck'ed had been fired 3X. That should have been enough to detect case streaching if I had a headspace prob. I think in a.m. I'm going to disassemble the bolt again. Thomae, I think that you will find that a spring like a f-pin spring will loose strength from being left compressed for long periods of time or being exposed to high temps.(don't believe temp. has caused any problems here,it would need to be much higher than inside the rear window of a truck.(gun rack) Can't do any range work until next week, I'll let you know what happens. Glad I"m getting to work this out before it's rechambered or rebarreled. Thanks everyone,Wish me luck Paul
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"Thomae, I think that you will find that a spring like a f-pin spring will loose strength from being left compressed for long periods of time or being exposed to high temps."
Lots of people want to believe that, but since the early 60's, firing pin springs have been made from "rocket" wire. Rocket wire as it is known, was developed by NASA and soon replaced music wire springs which were known to take a set. Even in the fired stage, the firing pin spring is still compressed @20 lbs. For heat to damage the temper, it would have to be in excess of 350 degrees. I check every main spring when I rebuild actions with a spring scale and have yet to find one that is below specs.
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Sorry it's taken so long to get back with ya'll. I've been fighting compuker problems, one after another, think we finally found it. After numerous things I finally streched the firing pin spring +- 1/2 in., that got it, no more misfires even with the batch of cases that were causing the problems. I haven't changed anything else, dies,primers,seating depth, nothing. Maybe this spring wasn't up to spec. or who knows what the prior owner did. Guess I'll be ordering a new f-pin spring soon. Thanks everybody for the help, Paul