Cannons 109E firing rate

Concerning the canons of the 109 my observation is that in 90% of all cases when I give a broadside shot (aspect angle 90% seeing nearly top view of target plane) with canons at a close target (60m) or medium distant target (100-130m) my canons just don't hit. For me it is basically impossible to score a hit with canons by letting a target fly through my bullet stream. I only score very few hits with my machine guns.

Somehow I have some doubts if the cadence is correctly modelled. I may accept that few cannon rounds hit - perhaps only one or two and that occasionally the target just flies through. But really almost in any case? This seems to me very strange.