The Nuke is a 9mm-dedicated upper, based of the Colt 9mm 633 "breifcase gun" that was purchased to defend nuclear power plants within the continental United States. 
 
Differing from a regular slicksided upper the Nuke has no cam groove, nor does it have a gas tube hole. 
This is to prevent gas from venting out of the receiver and into the handguard area, which is espcially usefull when running suppressed. 
 
For pistol calibers only- will not accept any rifle caliber or direct impingement parts. 
 
Machined from billet and available in Black Type III hard coat or bare bead blasted.
Does not have feed ramps