CNC Warrior does say on the Knurled Compensator page that you should tell them if you want it for a 2008 and they will chase the threads. FWIW, my Phantom flash hider from them went on fine on one 2008 but on a second one I had to chase the threads of the hider by using a screwdriver as someone here mentioned (screw on until tightish, back off and blow / clean out / oil threads, repeat). I want to get a second muzzle device instead of the nut I have on now and I saw that the knurled ones were on sale - I'm trying to decide between that one and just getting another Phantom style.