If I do anything to my Box Stock Ar15A3 heavy barrel carbine  (Model #6721 I THINK), I am wanting to do the following.
1.  Add BUIS to take the place of the factory detachable carry handle/rear sight.  Which ones should I look at.
2.  Replace the factory hand guard for a new one with picatinny rails.
3.  Add a vertical fore grip to the new hand guard.
4.  Add a light to the rail or get one built into the fore grip. 
Now like I said, this is a stock Colt carbine.  What else should I consider/do to make it as dependable as it can be?  I don't want flash/fancy gimmicks, just dependable functionality.
Last edited by SkunkHunter; 02/15/15 08:03 AM.