Critical hits and the head
Something I've just noticed.
Critical Hits come from rolling doubles on Melee and Ranged tests with positive SL. Since 96-00 is always a failure, there are eight ways to critically hit.
Because this is a "roll-under" system, the lower numbers are far more likely to be rolled. Even if your skill is low, a 11 is probably always a success, but unless you are superhuman, a 88 is probably always a failure.
Looking at the hit location table (p.211), the most likely location for a critical is therefore the head!
Don't forget your helmets, hive rats!