The P-51D Fixed reflector Gunsight has a 70 mils ring (70 ft. at 1,000 ft.)
German fighter wingspan is (+/-) 35 ft.
So, a German fighter wingspan filling One Rad, or half the ring, is at ~ 1,000 ft. range.
Pull 2/3rd's-of-a-second worth of lead and give'em a half-second burst.
...which should be 30+ rounds.
Bowie