I have often wondered why the RAF used .303 rather than the .50 cal. Both made by Browning, was it a lack of ammo supply at that time of the war?
The Hurricane wing could easly fit .50 Cal, in the Spit it could be a squeeze, but the Mustang with a similar cord wing managed it. And the MkV spit managed to fit cannons, not sure if it was the same wing as the earlier ones?
But if you can fit cannons you should easly fit .50’s.
Would having .50 fitted to Hurricanes made a difference in the BoB?
I think it would have made a huge difference.

So we’re just going to discount the Spitfire “E” wing, which was fitted with a single 20mm cannon and a single .50 Browning alongside it?