But one thing I've always wondered with American cop shows-  how on  earth they shoot so badly? And why they n ever shoot to leg or arm?  Always to kill.
		
		
	 
Because an arm or a leg are much smaller targets than a torso.  A cop/detective/agent trying to stop a perp is always going to be trained to aim for the centre mass, because they're more likely to hit it, and even if it's not a kill shot, it'll certainly slow the bad guy down.  
(the down side is, that if your target is wearing body armour/bulletproof vest, then it might not kill them outright, but again, it'll slow them down)