Pierced Primers/.454...?(pics)

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Started off with 17grns of Blue Dot working my way up to 18 (19 is listed as max). Starline cases, Winchester primers and a Hornady 300grn XTP bullet fired out of a Puma M92 rifle. At first I suspected a rough firing pin as the rifle was new, appears to be nicely rounded though. 1\4 primers look like this.

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Hard to tell with my s**tty pictures but there is a pinhole in the very deepest part of the strike. I guess the only other culprit would be high-pressure...? I used a caliper and compared the cases to some 1f Hornady brass, a load which I am trying to duplicate and dimensions are almost identical. I really wish my Chrony would have cooperated so I could have some data to help figure things out.
 
I noticed this on a couple of my 45 colt cases(22.5gr IMR4227) when fired in my puma and thought that maybe it was s**tty primers or too much pressure for a large pistol primer. I got pinholes in the middle of the firing pin strike but only a couple that I noticed, not nearly as bad as your situation it seems.

Looking at your problem as well I'm thinking maybe the firing pin on them hits to deep and resulting metal fatigue cracks the primer? Or actually maybe if it hits a bit too deep the anvil weakens the middle of the firing pin strike? Doesn't seem like it should but one never knows. I thought my situation was just a random isolated incident.

Afterthought: just looked at a box of +P 45 colt I ran through my Ruger SRH last time I was out and one primer out of 50 is pierced in the same way. I do notice looking at other ones that it has a little bur on the firing pin so I might have to take care of that. Next time I'm out shooting my Puma I'll let you know if I get some pierced primers and how many.


*edit*

Ok I just dumped out the primer catchment on my press(still has the primers from my last batch of 454 in it.). Using 29gr of H110 and CCI small rifle magnum primers not a single one is pierced. I'd say 30-40 of these were run through my puma and the balance through my SRH(batch of 100). Strikes look much lighter on the primer than on the 45colt primed with remington large pistols.

Are you using magnum primers? That might be the issue as my large pistol primers aren't magnum and my small rifle are.
 
CCI 450 small rifle mag. are the thickest and hardest small rifle primers you can buy. I use them in my .20 which was giving me primer peircing problems.
 
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