What are the most desirable Colt prebans?  Are the lower receivers that are marked 'AR-15 A2 Gov't Carbine the most popular and highest price?  Are slabsides more or less desirable.  How about the Sporter Match rifles that don't are preban but don't have the bay lug?  What about large fire control parts and large screw like front pivot pin?  Are these that desirable?  Colt prebans have the largest price range from what I've observed.  I've seen them as low as $1,000 dollars all the way up to$4,000 dollars for an M-4 semi NIB.  Can someone give me the lowdown on Colt prebans?  Thanks.

It is important that the only thing consistent about colt prebans is there is no consistency.  As a general rule, I am no expert, a green label has bayonet lug, large pivot pin hole and raised mag well fence.  Blue label has small pivot pin, no bay lug and also has raised mag well fence.  The pivot screw can be replaced with a $4 item from bushmaster.  take out screw, throw away, put spring and detent pin and you are good to go.  Remember, uppers are meant to change out.  So having a small hole lower is most important. Otherwise, you need this little thing that goes into large hole to make it small and it usually gets lost.  Bayonet lug can be had on any upper as long as it goes on preban lower.  I own a preban blue label colt hbar.  I removed hbar, put on colt 14.5 flat top upper with bayonet lug.  I replaced screw with mil-spec pin.  I am ready to go.  Good luck.  I would not rely on the ASB to go away if you can afford the prices you are finding.  It is better to capture a preban now since prices are a bit lower and have it in hand versus the price skyrocketing if the ASB does not go away.  Get plenty of mags as well.  Good luck.