There is a simple glitch in the final area that can turn one of the hardest fights in the game into the easiest. Just stand where I do, shoot any who manage to find you (or have guns) and use rockets on the chain gun guys.
So this glitch existed back on the Xbox 360 version and still works on the Xbox One and PC. (and I assume other versions too) I've never seen anyone post about this, and I have only just now due to now having Xbox One's DVR ability.