Originally Posted by
Treble one
Just a quick reminder, that for years the RAF had armed their fighters with 4 x .303 machine guns-it was only the work by Sorley and his team that persuaded them, due to the increasing speed of aircraft, and the need to have more firepower to get a higher rate of fire and increase the chance of getting the number of hits needed to bring them down.
I'm assuming that canons were both a step too far (given we'd just introduced 8 x .303) and anyway, as early BoB results showed, were not fit for purpose in 1940 (not belt fed and didn't really fit in a Spitfire wing as designed). 'The Most Dangerous Enemy' by Stephen Bungay discusses some of the development story and issues associated with arming our new monoplane fighters.
Yes - the .303's lack of 'punch' had been demonstrated in trials on a reasonably intact but very much Cat 5'd Blenheim, leading to much furrowing of brows; the Air Staff knew that the .303 wasn't up to the job - or wouldn't be for very long - before the Battle started. GF Wallace covers this in his book on RAF weapons, as does Tony Williams on his website - from memory of his observations, the Air Staff had identified the 20mm round as the best option for dealing with armoured aircraft some time before the war started, and not long after settling for the 8 x .303in fit for the Spit and Hurricane.
(As an aside, Tony Williams makes the point that the M2 Browning was more reliable in terms of stoppage rates even once the HIspano had been sorted out; the US -made Hispanos [digression] were even less reliable)