this is from our friend tom, 98z5v, about putting those on: To put those on a .308 AR, he'll have to cut the heatshields to get it to fit. It's back by the chamber area, because the chamber is larger then the 5.56 guns. About an inch or so forward of the BACK of the handguard is where a straight cut needs to be made in the heatshield. No material really needs to be removed, but you have to "notch" that heatshield so it can flex away from the rest of the heatshield, and still get on there. As always, some minor fitting of the plastic areas that mate up to the front mount, and rearwards at the delta ring, might need to be made. The primary problem for the .308 is getting that lower hanguard around the fatass .308 chamber-area of the barrel. That heatshield is what hangs up. good luck man, edge