I did this like 15003450 times before I found a trick that worked.
Sit behind the tipped over couch. You know hes only ever going to be in the top 3 windows, and this gives you a perfect view. You have to be a quick shot, though.
Now, just strafe left/right a short distance very quickly. Like, just spam A-D really fast. He won't be able to hit you right when he pops out, giving you like a 10th of a second to shoot him first.
I played on Hardened and after wounding him a thousand times in various other spots that I thought were tricky, I tried this and got it first try.