[dodgetheram]

I'm no expert, however, my friend has an KA colt m4, and recently changed his hop up and he used a madbull. It went in perfectly, I belive the KA is TM compatalbe. So most aftermarked TM parts (or clone) will work. On the other side, I have read that alot of people have to do light custom work to the hop up or where it fits to make a good fit.