The Colt 6940-P is a "piston" driven, monolithic 16" upper barrel assembly carbine style rifle. I don't believe it has been commercially offered by Colt for several years, occasionally one can be found on GB. A Colt/6940-P marked lower should work fine with a standard, available, "direct impingement" 6940 upper. Cost for new Colt/6940 complete upper probably $600-700, or just purchase a new 6940 rifle between $1200-1400. Hope this helps.