Quoted:
It's been many years since I've seen a Colt (or any other manufacturer's) bolt carrier without the foward assist serrations. SP1's in the very early 70's had the serrations, and did not have the foward assist assemblies. Foward assists did not show up on AR-15's till the early 80's.
The M16 bolt carriers had them, and it must have been cheaper to produce the AR bolt carriers with them the without them.
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Absolutely correct. Colt never made any "AR15" parts in and of themselves. They've always just modified M16 stuf to conform to their idea of what an AR15 should be at any given moment in time. As soon as the A1, with the forward assist was adopted, all AR15 bolt carriers were simply made from cut back M16A1 carriers, with the left over early upper recievers w/o the forward assist. I seriously doubt that any owner of an original AR, without the assist cuts, would be willing to part with his original carrier.
There is one hope tho. Since the military has been selling off M16 and M16A1 uppers, as they convert the old pieces to the A2 format, he might be able to latch on to an early, Air Force contract, M16 bolt carrier. If he can find one, tell him to expect it to be well used, and probably very pricey. So far as I know, that's his best shot at a Colt unnotched carrier.