Army of Two (EU)

Ok this is a pain in the arse!!! It took me a good few attempts to get it.

Right set it to Recruit differculty and then pick mission 8. Go right to the end and shoot all boxes and TV's on the way to help you in another achievement ; ) then once you get to Dalton keep running around the edges of the map til you get near him. Then what i did was go in the bit at the back where it provides cover and he ran right infront of me but on the other side near the middle bit also in cover.

When he pops his head out shoot him with the fully pimped .44 MODEL 29 handgun. It took about 6 shots for me as he had alot of life but he when down in the end and the achievement pops as soon as he goes down.

I would also say be careful of the rocket launcher dude as he's a right dickhead. Also just keep trying your get it in the end ; )