Guys, read all of German Salazar's stuff you can get a hold of. Some is on his blog, and some on threads on BR Central.
I think German would be among the first to admit that we don't have the complete story yet. There is also Phil Bower's (4Mesh) writings on a couple 1,000 yard threads, where he and others recommend LR magnum primers for good ignition with large cases and slow powders, and attending to striker issues
Why all this general stuff on a thread asking a specific question?
Because ignition is at the root of it, and after over 15 years in this game, I'm discovering that I don't know as much as I thought. Cookbook thinking takes you pretty far, but occasionally not far enough.
As far as primers go, I think that the physical size of the primer is irrelevant. May have some slight effect on primer pockets loosening. Dunno for sure. Beyond that, it's just how much "ignition stuff" is in the primer, where "ignition stuff " is more than just the quantity of the priming compound. German and 4Mesh define it better than I can.
German's tests have shown we can finally, with the Wolf LR, get a LR with about the same *ignition stuff* as a hotter SR. That's exciting, because now, there isn't a big hole in "ignition stuff" between SR and LR.
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Flash hole size. Also seems to be a factor, too many people have reported changes with drilling/uniforming flash holes to invoke placebo effect. The shape of the flash hole, that is, funneling, may also have an effect for cases with at thick web. Most of the cases we use don't have a thick web, so this may be down at the noise level for the stuff we shoot.
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Mechanical parts of the ignition system. Dwight Scott & a few others found that by increasing the mass of the striker in a popular action, groups shrunk. 4Mesh increased the fall of the firing pin, also with success. It seems you can't do it with the spring alone.
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"Oops, I misdiagnosed (part of) the illness." Here's me, confessing, to illustrate.
For years, I've been plagued by vertical. Not much, but a little. I was reassured by Tony Boyers statement that a gun with a little vertical agged better. Probably true, but I wasn't agging quite well enough. I blamed the wind at long range. I'd get my wins, so it had to be conditions, right? Or maybe ignition? At short range group, the yardage or 2,3,4-gun wins were missing, but I'd win small group often enough to think everything was OK, I just couldn't read the wind well enough. Yes, it is vertical, but at the ranges I shoot, I believed vertical can be caused by wind. Well, it can, but how much? Maybe most of it isn't wind?
Started shooting short-range score. Too many 10's that were a cat's whisker away from being X's. For me, shooting score drove home that there was a problem, where shooting group didn't.
Made a post on BR Central about shots popping up. Gene Beggs suggested attending to the rear bag. I put a piece of long-nap felt over the rear bag, slickest stuff I know of. Secondly, in shooting PB score, I noticed that in moving the rifle from target to target, I was sometimes cheeking the stock, sometimes not (I *claim* to shoot free recoil). Paid attention to that. Doing both those things, the problem's been cut in half.
Back to long range. Keep the felt on the rear bag. Shifted to magnum primers. Still vertical, but sometimes less. Better rear bag? Better ignition? Don't know for sure. Generally, shots are now clumping -- 4-5-6 here, 2-3-4 there. With 210s, it was just a string. Something's going on. Maybe it is the firing system. Whatever, I'm pretty sure it isn't just one thing, like primers alone.
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Reforming brass.
Wouldn't it be easier to get an end mill of the right size, put a stop on it, and ream out small rifle primer pockets to large rifle, rather than reforming cases? I'd want to use a mill or lathe, but these days seems most people either have one or have a friend with one.
FWIW
