One-Hit Kill: Your mileage will almost always vary, given the amount of variant tech out there, but a sluggun – and the S-11i Mamabear in particular (see: BFG) – will do this to most regular infantry (they are, after all, designed as anti-materiel weapons), and one in which you put antimatter-grenade slugs will one-hit kill just about anything… assuming you’re in the sort of war and on the sort of battlefield where they let you use weapons like that, which tends to be the problem there.