we use d12 for damage results and use optional rules for critical hits..
example:
DAM 1 (9mm) 10% chance of critical hit(a critical hit means you loose every HP down to 0 and then take the rolled damage) double chance of critical damage for head/chest and abdomen
DAM 4 (7.62mm N) 40%
DAM 9 (12.7mm) 90%
etc.
http://thebigbookofwar.50megs.com/DOX/0-House%20rules/
chekc out melee damage rules 2,1