[TML] 20mm

[Anthony Jackson]

GDWGAMES at aol.com wrote:
>>> How big does an alien need to be to use a 20mm as a standard long arm?
> IMO, not much larger than a human.

Kind of depends on what you mean by 'standard long arm'. Also on what 
sort of 20mm you're talking about. A 10 gauge shotgun is almost 20mm.

Controllability can probably be estimated based on (bullet mass * muzzle 
velocity / body mass). For an assault rifle, that ratio shouldn't exceed 
0.05 m/s. For a semi-auto battle rifle, 0.10 is fine. For a sniper 
rifle, significantly higher values are possible, but getting over 
0.5-1.0 m/s is very dubious.

For comparison
5.56x45: 3.8 kg*m/s (0.05 for an 80 kg human)
7.62x51: 8.0 kg*m/s (0.10 for an 80 kg human)
14.5x114: 59 kg*m/s (0.74 for an 80 kg human)