[ChrisMAg2]

Bill to me this assumes a shortend abbreviation for Fla-maschinen-(waffe), which are AA-machine guns and cannons in general.
Or the observer could not identify it exactely and just mentioned a weapon with a higher rpm rate, but lower then a MG, unaware he could have used an expression like "mittlere" (3 - 5cm) or "leichte Flak" (≤2cm).
Also the Germans did distinguish calibers upto 2cm as MG (MG 15, 17, 131 MG 151/15 and MG 151/20, MG FF) and above that as MK (MK 101, 103, 108). The famous allied Oerlikon 2cm AAA would have the german MG FF as counterpart, from which the latter was developed. But the 2cm FlaK 29, 30, 38 are regarded a "Kanone". Confusing, isn't it?