Today's entry into the Halo 3 Weapons Guide is the SMG.

Clip size: 60
Max capacity: (not dual wielding) 240
Rate of fire: ~15 rounds per second
Rounds to kill(body): 24
Rounds to kill (head): 24
Rounds before melee kill: 10
Rounds before close frag nade kill(body): 8
Rounds after close frag nade to kill(body): 8
Rounds before far frag nade kill(body): ~14
Rounds after far frag nade to kill(body): ~12

Notes: The same overall concept applies as when using the Assault Rifle. As the enemy moves further away, you need to shorten your bursts more and more. The problem with the SMG, of course, is that it is much less effective at range than the AR. Luckily, the sheer number of bullets it puts into the air makes it a better choice then the AR at extremely close range. Dual wielding has a noticeable negative effect on accuracy.

For demonstrations of the SMG, see these short films:

SMG Range Demonstration
SMG Kill Demonstration