Quad AA.

[chuckfourth]

Hi BaggyPants
I know they didnt have spare barrels because if they did then they would have been used and this would have given the 50 cal the same practical ROF as the 30 cal which it hasnt(40 vs 150 rpm). (not forgetting both have the same cyclic ROF) the 50 cals low practical ROF is proof they didnt swap out the barrel.

But the Low ROF didnt matter, because on the ground tripod mount it wasnt used as the coy sustained fire MG this was the 30 cals job. It used as a heavy punching automatic cannon.
On a tank turret it was simply decoration, there were no planes to shoot at and the british ditched them as impractical. It makes a passable AA quad mount as the engagement time is low but when the 50 quad is shooting at ground targets, the 20 mm outclasses it because of its higher practical ROF.
Best Chuck