First off, I'm very happy I found this site. Posts are helpful and nobody seems to be carrying an attitude, which I appreciate. I bought a used LR-308, apparently never fired - absolutely 100% condition. Smooth sided upper, no forward assist, no dust cover, and an 18" heavy barrel. I don't have a caliper, so using a tape measure the height of the rail above the surface of the upper receiver appears to be 3/4". The front hand guard which has only a swivel stud for a sling is 7.5" long. The gas block height is above the height of the hand guard and apparently the same height as that of the receiver rail. It has a standard A2 stock. I have already purchased a Magpul PRS in FDE. I'd like to find a rail system, and from the DPMS rep it would be a standard length free float, but he indicated that only a DPMS high style free float rail will work, and I will need to change the gas block to a micro. If anyone else has already gone through this changeout, and can confirm or offer alternative choices for the rail, I would be greatly appreciative. There are some feral hogs out there with my name on them who eagerly await my arrival.