Semi-auto Bren piercing primers - any solutions?

[dcollector]

Hi guys,

Anyone have an idea for a solution to this issue?

(It is a US civi-legal semi-auto Bren, using the striker system, not an open-bolt Bren.)

I am using the recommended S&B ammo - Bren is cycling nicely but rupturing the primer.

Thank you in advance for any suggestions.

*I'm going to try out some surplus Brit .303 ammo, that has tougher primers, hopefully that is the fix. I'll also try it with some PPU ammo.

[browningautorifle]

We often equate that sort of thing to excess pressure in reloads, that's factory ammo isn't it? I always thought S&B to be at the very top of the pressure curve in it's loadings.

Otherwise it would be firing pin protrusion, but there are guys here that can quote you what that should be off their noggen...

[dcollector]

Thanks Jim, this was 100% new manufacture factory Seller & Bellot ammo.

Yes, I posted in several forums on this question, as I really don't want to damage the Bren, apparently you are correct S&B are hot loads with weak primers.
I'm going to run some WWII Brit through it, and some PPU next week, heat that old barrel up and see what happens.

Thanks.

[browningautorifle]

WWII Brit through it, and some PPU next week,

Those should work fine if the WW2 ammo fires when it should. CCI makes military thickness primers I think...but I expect you just want to shoot factory. As for hurting a Bren, I loaded an old reload into an Inglis 8mm once...another man's gun and his cheap ammo gatherings...and when it detonated the mag turned into a tube launching the base and spring. The case was destroyed, the gun was unhurt. Functioned well as if nothing happened. Peter L will be able to give us some sage advise here if he sees this post.

[tiriaq]

Perhaps the firing pin is insufficiently supported, allowing the metal to be blanked back into the firing pin hole in the bolt face.

[Brian Dick]

The Bren firing pin is designed to stake the primer in the pocket after firing to remedy the problem of backed out, spent primers jamming them during trials. I don't have much experience with S&B but guessing if you change ammo, the problem will go away.

[Peter Laidler]

Never seen that with any Bren but caps-out was a problem until they solved it, as Brian says, by staking the cap in place during ejection and knocking the cxxp out of it, to distort it when firing.

Could the striker hole be enlarged? Failing that, the answer must be excess pressure blowing back against a weak primer.

I did see a Bren accidentally fired without a locking shoulder. Te breech block was not locked up so came back and split. The magazine and rounds went upwards and onwards and are probably still in orbit around the moon. The blast from the round exploding in the breech caused the body to bulge and the gun being written off.

The locking ramp at the rear of the breech block ran hard into the rounded rear shoulder of the empty locking shoulder housing and stayed absolutely locked into place. So there was no excuse or waffle explanation that could explain it all away. But as the person who left the locking shoulder out was a young REME Craftsman, The Field and eventually, Base workshops were able to send it on its way to the great scrap yard in the sky. After all......., dog doesn't eat dog.