When not locked into an engine hollow airscrew shaft, the Mk108 was set for 400m or 500m to facilitate not having to worry about elevation as much. Mountings in 110 were at 400m, 163 400m, and 262 400m and 500m for the respective banks.
The AAF determined that 1200ft or 400yd was the effective maximum range in combat for the 50cal. By 400yd the round slows down by 2\3 its initial velocity loosing 1\2 it's penetrating power. In the first 1\2 second or 400yd your drop is about 4ft with a 4ft dia. dispersion. While by 1sec, 800yd, the drop is 16ft with dispersion about 12ft dia.. These dispersion numbers seem to be maximum dispersion. Effective dispersion assumes 75% of the rounds are in a circle half the maximum diameter.
The closest you get to this with the MK108 is at 250m(273yd), drop 1.35m(4.4ft), and dispersion 5.5m(18ft). It's chemical content makes up for the loss of velocity at range if you can hit anything. At 400m(437yd) the drop is 12ft with a dispersion of 30ft.
50 cal - 2700 ft\sec
Mk108 - 1640 ft\sec
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