I got to wondering. . . has anyone done a bolt-action .308 upper for an AR-15 yet? I've seen semi-auto uppers for just about anything that will fit in the AR-15 magwell, bolt-action uppers in .338 Lapua up to .50BMG, and even pellet-gun and crossbow uppers. Seems odd that .308Win/7.62NATO would be left out, even if there are the AR-10s.