I've seen references on the board to the older Colt bolt carriers that are called "full circle".  Are these considered of better quality than the new bolt carriers?  They do appear to sell for more money than the newer bolt carriers.  Any information would be greatly appreciated.  Thanks.
-NC_TarHeel

Dunno if they are any better, but the full circle bolt carrier looks more like the M16 bolt carrier, personally I think the ones that aren't full circle just don't look right.

"Full circle" refers to looking at the carrier from the rear.

For many years, the semi bolt carriers were full circle but were missing material from the bottom that the M16 carrier has that would trip the auto sear.  It appeared to have been simply machined off.  You could, however, convert the semi carrier to full capability by buying an add-on to extend the carrier bottom inward.  It's hard to describe.

The new ones are simply missing the rear lower half so you can't do that any more.

Also the material is removed to clear the block in the Colt lowers.