Semi-auto Bren piercing primers - any solutions?

[MGMike]

Forty-plus years ago I experienced numerous "ripped open" primers exactly like the ones you have shown. Mine were fired in a very well-worn two-dovetail Mark 1 full-auto gun with a Mark 1 barrel. The ammo was military surplus .303, I believe from India or maybe Pakistan. Best as I recall, the headstamp was K 50 (Kirkee?). The ammo was imported by FedOrd in California; I bought a full steel case of 3,000 rounds loaded in single-use Vickers belts. The cartridges were very clean Mk VII; I broke a couple down and found them loaded with cordite. The gun functioned fine, but the peeled-up primers obviously were not good for the bolt face, and neither the cordite nor the corrosive primers had much to commend them.

As to cause: right off the bat I blamed the ammo: seasoned (and therefore brittle) primer cups. Later, after some separated cases, I followed the procedure in the Armourers’ Wing Précis SA/7, and discovered that the gun had considerably excessive headspace; inspection also revealed a broken piston post buffer spring. What if any role these latter two played in the torn primers I cannot say, but I suppose it is possible that the broken spring did not properly support the firing pin after cartridge ignition, and perhaps the extra headspace gave the primer more room to tear.

Anyway, I quit using that ammo. A larger locking block cured the headspace, and the broken spring was replaced. After that the gun worked extremely well.