I have a Colt Match Target M4 Carbine. Model MT6400R1 (UPC#098289025258). I would like to have some work done on it but it has the monolithic upper and my the shop does not have the specialized tools to disassemble the LE6940 uppers and remove the barrel nut. Colt Customer service has replied that they cannot help identify a supplier. THe only producer that I have come across is (was) Arrington Accuracy Works and they appear to be out of the gunsmithing business. Does anybody know of a supplier of the specialized wrench to remove an LE6940 barrel nut?