I had one of the Gibbs in .308. Front sight/flash hider assembly was canted very far to one side requiring the windage adjustable front sight to be moved ALL the way to the right just to be on POA at 25 yards. The mag would lock into place but would not seat high enough in the well for a round to strip off when the bolt was closed. It would only load if you applied pressure to the bottom of the mag. The ProMag extra mag I ordered to fix the problem, made specifically for the .308 Gibbs, would not work at all. The rifle would also not extract worth a shit. The rounds would get stuck on the inside needing a lot of strength to pull them out. Yes I tried 7.62x51mm and .308win, problem same with both.
STAY FAR AWAY!!!
YMMV
drew