Pierced Primers in Factory Ammo

vtmarmot

vtmarmot

P Magoon, Livin' Free NH
I bought and restored a 1943 British Enfield. Needing ammo, I bought a bunch of Prvi Partisan 174 grain FMJ. I figured I'd shoot it up and reload the cases. Today I shot the first 16 rounds. About 4 had pierced primers and another couple needed multiple strikes to fire. I attribute this to inconsistent primer cup thickness rather than a fault with the firing pin or spring.

First question - has anyone seen this kind of thing with this or any other brand of factory ammo?

Second question - what is the effect of repeated pierced primers? I saw no signs of escaping gas.
 
303

The headspace needs to be check by a gunsmith. The firing pin nose will become gas cut and pierce more primers as it get rough. The .303 British rifle may have a very large chamber. The round head spaces on the rim. The shoulder will blow forward on firing as in the photo. When reloading this round, its best to neck size only. Or have custom full length sizing dies made, by sending 3 fired brass to RCBS.
303.jpg
 
Thanks for the Info

Thank you. I've never had anything like this happen before. I plan to examine and measure the cases today vs. fresh ammo. I will also get it checked out by a good gunsmith, when I can find one. They are getting scarce in this area (central VT and NH).

I will also push out the spent primers and see if I can measure the cup thickness. It seems odd that some would pierce and some would require multiple strikes to fire. I have quite a bit of this ammo and I hate to think that I'd have to break it all down and reload with quality primers. That will be a lesson to me about buying cheap stuff.
 
I would try a different brand of factory ammo. See if its ammo related. A gunsmith can also check the amount of firing pin protrusion to see if its correct.
 
Much more research to do

I have just begun to research this issue. I had the rifle parkerized, and I'm wondering if that made the tip of the firing pin rough enough to cause primer piercing. It was only 3 of 16 rounds that had it. Then there were the two that took multiple strikes to fire. I popped out the primers and the cup material is uniform in all of them at about .013". I suspect inconsistent hardness in the material. Other posters on other forums report pierced primers with Prvi Partisan ammo. Rim thickness is uniform and within acceptable limits. The fired brass has a sharper shoulder than unfired and the shoulder is moved forward but the necks are the same length. It looks kind of like an Ackley Improved version of a .303 without the body taper reduction. I will certainly look into getting a custom full length die made or perhaps a bushing full-length size and neck die like a Redding S-type.
 
You might want to check the striker protrusion. My memory is not to be relied on but say, 0.055".
 
You stated it isn't a cause, but a weak firing pin spring IS a possibility. Weak mainsprings cause inconsistent strikes on primers, resulting in failures to fire. Blowouts also occur if the spring is too weak, as the only thing supporting the primer strike area is the firing pin - too weak a spring, and pressure inside the case pushes the strike area out. The two can also be related: blowouts throw chunks of primer inside the bolt, resulting in light or no strikes on following rounds.

Can't help with firing pin strength on a Lee-Enfield (should not be hard to find), but strongly advise disassembly of the bolt, and thorough cleaning of the pin assembly and the inside of the bolt using an aerosol cleaner. (Carburetor cleaner, Gun Scrubber, or other similar cleaner.) Repeated cleanings are hightly advised. On reassembly, the only lubrication applied to the firing pin assembly should be grease on the cocking cam.

Hope this helps.
 
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