vometia, about luftwaffe using mostly cannons, in later stages yes, but in earlier stages of WW2, they used both. Bf 110 was they main ground attack aircraft and had 4 machine guns + 2 cannons.
I know they used to use the MG15 quite a lot: I mainly remember it as I used to confuse it with the MG34 from a distance, which it wasn't. I guess the differentiation with "cannons" is also somewhat semantic and for me it's the differentiation between standard rifle ammunition of the time (.303, 7.92mm etc) and "bigger boys came". In the latter regard (and apologies for what is a rather obscure reference for anyone outside the UK: Harry Enfield and Kathy Burke's "Kevin and Perry" characters) largely in the form of the likes of the 20mm Hispano-Suiza which was a bit like a Bren on steroids, and additionally blurred the line in having a really very quick firing rate, about 700rpm IIRC. Okay, a bit pedestrian compared to the Vulcan (I'm imagining another comedy series with the Californian scientists saying how awesome it would be to make a Gatling with an electric motor and huge ammunition) and even some actual aircraft cannon at the time, including some scary 75mm jobbies,but pretty lethal nonetheless. AFAICT, with that caveat that aircraft aren't my forte, the HS guns eventually ousted the .303 Browning M1919s as the RAF's mainstay. Contrary to the "less is more" cliche, sometimes more is more, it just depends what you want more of. Well that was very philosophical of me.
