The 37mm on the P-39D fires multiple rounds (repeatedly) when you only fire it for a fraction of a second. Fires 2 rounds at once. [EDIT: Like the old yak9t bug] I'm not totally sure about how the ammo count is affected, sometimes it looks like it fires 2 rounds for only 1 round's worth of ammo, and sometimes it fires 2 rounds and takes 2 off the counter.
I got several films of this offline just now.
Second issue with the 37mm gun is the super-excessive cone-o'-dispersion. Even at a very close-and-friendly 100 yards, using the .target command, the round dispersal with single-shot sniping is off the charts. So wide that you can, in fact, MISS the target you are perfectly lined up behind. Even if it's not moving. Even if YOU'RE not moving. Dispersal on even the first-round-fired (which should be the most accurate because it doesn't have airframe shaking etc) can go way off in the boonies, and even firing a single shot, waiting, and firing a single shot can send rounds AROUND a target even at very close range.
You can't get the "cone" down to the area of your target unless you fire at the target under 60 yards (where you risk blowing yourself up in the MAs).
Is this even remotely accurate? I know the gun's rounds "drop" a lot, but is this historically accurate that the aim is so bad, or is this some bug nobody noticed until now?