Shooting directly from behind doesn't give good results and it's not a bug, it's supposed to be that way. There's a bunch of empty space there with the exception of the occasional armor plate to further ruin your day...it makes sense, the aircraft designers covered the rear positions with armor and guns because that's the easiest place to shoot from.
I have no problem shooting down 3 Dorniers and still have ammo left to damage a fourth, which may or may not crash later on.
The trick is not to shoot directly from their 6 o'clock position. Come in slightly from the side above/below. The way i get kills is not by making things explode. I either hit fuel tanks and engines while coming in sideways, or i kill the crews if i'm coming in from above.
Parking on their tail is certainly doable now that the AI gunners "feel" fear and have more variables in their experience, but that doesn't mean it's the optimal solution.
I get similar results with every other aircraft in the sim. I can chip away at a walrus or a gladiator with the G50 and it won't really matter, but coming in from the sides (slightly so, you don't have to be exactly perpendicular to their course, just come in from their 4-5 o'clock instead of dead six every time) i can kill the pilot more than half the times. Similar for attacking heavier aircraft like the Sunderland and Wellington with the 109 and 110.
Don't worry about maximizing time on target if your angle gets you no results, come in from a different angle even if that means a shorter amount of time spent shooting.
Even in short bursts, deflection shooting is your friend
