Same with me,
But I noticed if you get a vehicle like a M1A1, add the EH
And shoot it with a law it goes down with one hit,
(baring in mind it usually takes a s*it load of laws, 1 AT round and a hell of a lot of cursing to bring down, only to be shot in the head by the last fleeing crew member)
Therefore it seems that the "hit" EH only works with heavy weapons, on vehicles.