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Okay, so a relatively stupid question.
What is the correct, normal, gas regulator setting for using 174gr Mk VIII ball ammo? Figure ISA std atmosphere, sea level @ 15deg C. This would be for an original, unaltered WWII production fully automatic Mk II Bren using a Mk II barrel and Type 3 regulator, as issued.
I see published references to settings of either #1 port, or #3 port. So which is correct to provide normal standard starting point?
-TomH
Would you not have to balance the individual weapon to see? I would start in the middle and see if it operated...then maybe adjust from there, up or down. No more gas then needed.
We didn't 'balance' the guns as we did the L7/GPMG's but we woulkd expect a Bren to run well on 2 or 3. If it did run well on the smallest hole, all well and good. The L4's should run on 1 or 3 but there'd be no complaints on 2 or 3. If you could only run on the biggie, then it was a sign of trouble ahead.
During the last days of the L4's we were also getting some odd ammo coming on stream......... But I'm going off at a tangent now
I run my Inglis Mk.II and EFD L4A3 on #2 here in SC with no problems with both Mk.7z and Mk.8z. I had to turn the L4 up to #3 while doing a demo near the Blue Ridge in Virginia a few years ago using L2A2 ball. I'd guess the elevation changed things a bit. When we installed a new Mk.3 gas cylinder on a friend's EFD Mk.1 gun several years ago, it was running fine on the #1 setting but after a thousand or so rounds, it broke in nicely to the #2 setting, even in the mountains. I ran it down here in SC immediately after repairing it and had to turn it back to the #1 setting because the brass was cutting chunks out of my bench during ejection!
The design of the gas regulator on the L7 GPMG is designed to be balanced in any conditions with 12 gas settings. The U.S. M240 only has 2 settings which is simpler but from an armorer's standpoint, much harder on the guns.
Like the UK GPMG had 12 settings, the Canadian C6 only had 6 I think. The new ones have 3 I think and have been pinned in place, like the armored version...much harder to adjust and without fine adjustments, much harder on the mech.
There's a good reason for the 12 gas settings on our L7 guns. To be honest, I really didn't understand the complicated GPMG gas regulator system until I was told to prepare/oversee a lesson for a new instructor - about the bloody gas regulator! I sectioned a length of L7 barrel, marked it up, sectioned a gas regulator so that the collars stayed in place (takes a bit of thought.....) and there it was.
I learned that if you are using your own supply of well documented, tried and tested ammo, you can get away with 2 or 3 settings. But life ain't always that simple and some nations idea of 'NATO ball' isn't the same as others..............
I agree with multiple settings Peter. When with the old gun we tried to set them up...the book said to do "This"...if you had an old worn gun, you had to go by sound of firing. It's almost a pitch. Therefore you had to close up the gas more than the book wanted. Then you got 4 tracers in the air per burst during SF role. Otherwise it was running like the old .30 cal. Once they changed the gas system, you couldn't make it work right so...off to workshop...
During the Base workshop overhauls we used to test them in a depression pit where you'd fire a magazine in bursts vertically down and the gun had to operate the mechanism from vertical on gas 3. When my son was young I used to take him in and let him fire a few like this as it meant a chance to fire one from the waist. We used to have another test to simulate elevation/AA fire. Any gun that would only function on gas mark 4 was sent back for further examination.