Ah thats really nice, I might have to switch to that handguard, I haven't finished modifying the Midwest industries handguard on mine, it's a pain grinding down the mount to fit our bigger 308 barrels.
Yeah it's the ace clamp-on. It's a nice solid piece but if if you buy directly from ace, AKA riflestocks.com it takes a long time to get it; think I waited almost 2 months till it arrived.