Semi Bren Primer Flow

[ActionYobbo]

Peter you are trying to reinvent the wheel here. This problem has popped up before in striker fired brens its the firing pin.
If i am wrong I will buy a round of beer for everyone who has posted above here

I know where you are coming from Peter but the semi auto bren firing pin has more in common with the SKS than it has with the original BREN. Take an SKS with an eroded firing pin tip and lengthen the slot for the retaining pin so you get FPP and you will also get pregnant primers.
In this case the slot in the firing pin is cut too far forward allowing excessive rearward movement of the firing pin. You have 12oz of firing pin
and striker against 2 ton of pressure on the primer cup. Pure physics at work here

To Mr alterego can you post a picture of your bolt face with the firing pin retracted to its rear most travel. I assume you have a spring in the front of the firing pin to hold it back and by your description I also assume you are using mightylime's setup