Reloading .303 British : Mk VII & Mk VIII (Z) ball ammo (long)

Ammunition matching that description was the subject of a warning years ago. The warning stated this ammo could spring the action of an SMLE and that it had shattered a No.4 bolt head.

 

I have some FN long range MG loads that have a very unusual bullet. The boatail portion is long and extreme the base is tiny in comparasion . The ogive looks sort of fat, it would fill out a throat with little slack.

 

As for why they restricted Mk8z ammo to the MG, they found that when the average No.4 rifle had been fired with as few as 200 rounds of MkVII ammo using cordite that the throat was burned out enough that the boat tail Mk8 bullets would keyhole.

 

Major E G B Reynolds ran tests to determine what was going on when due to disrupted supply lines the Tommy in the field often had to use delinked Mk8z ammo till sufficient supplies of MkVII could be obtained.

Flame temperature of NC propellants is much lower than that of Cordite. Some will tell you different but that's because Cordite temperatures are usually listed in degrees Kelvin. Also Cordite can't be mixed with common flash suppressants, muzzle blasts from automatic weapons using cordite are more easily spotted and easy to tell apart from other weapons in battle.

The Germans once wiped out a company of central European ( Hungarian) Fascist conscripts they had armed with captured British weapons when German artillery observers saw the cordite flashes and mistook them for British troops.

Late in WW2 orders were cut to use Mk8z ammo in the BREN Gun during night operations.

 

 

For best results with boat tail bullets major diameter bore sizes must be close to bullet diameter. That's seldom the case with Lee Enfield barrels.

 

Chamber pressures for Mk8z in Copper Units is more like 48,000 CUP.