As BigMag says, you'll want to do a little modding. If assembled at face value the guns will be pretty much horizontal which doesnt look right. By carefully dry fitting the arms part between the gun and torso you can find an angle you like and glue it to lock things in.
For each gunner I embedded a magnet in the floor and in one of their boots (and did not glue the guns to their mounts) so that I can easily take them out and close the door if I want.