Rough concepts everyone! Rough concepts =)
So if you don't catch the head - It'll jump back into it's body and it will come straight back atchya. Longarm's head and shoulders rotate quickly, his body can move pretty well, but his arms are slow. You'd be thankful for that...
Now, alternatively, if you do kill the head - Longarm will get up on it's own and be pissed right off and stupid reckless. But of course - blind. This is dangerous but also exploitable. Outsmart the fatso.