Depends upon which NM barrel. If it is a USGI national match barrel, then it should fit. A Colt Gold Cup National Match does have a narrow barrel hood and will result in a sloppy fit. If you want match grade accuracy, get a gunsmith fit barrel and have it fitted. If you just want improved accuracy you can get a semi-drop in barrel from Wilson, Ed Brown, Storm Lake, Nowlin or BarSto. Heck, I have heard that Springfield Armory, Inc. match barrels are good.
