I recently had Firearms Service Center install a compensator and free float quad rail on my Spikes Tactical upper. And they did both of them wrong. And then argued with me about it. DO NOT LET THESE IDIOTS WORK ON YOUR AR-15. They know nothing about them. They did not index the compensator properly and they did not use shims behind the barrel nut. The compensator was easily fixed by an actual gunsmith. The barrel nut was likely over-torqued and stretched the threads on the upper. These good ole boys might be able to work on your hunting rifle, but I wouldn't trust them to install a LPK on a stripped lower.