And it would make silencers illegal in Colorado unless they change existing Colorado laws.
•C.R.S. 18-12-102 (Possessing a dangerous or illegal weapon-affirmative defense.)
(1) As used in this section, the term "dangerous weapon" means a firearm silencer, machine gun, short shotgun, short rifle, or ballistic knife.
(3) A person who knowingly possesses a dangerous weapon commits a class 5 felony. Each subsequent violation of this subsection (3) by the same person shall be a class 4 felony.
(5) It shall be an affirmative defense to the charge of possessing a dangerous weapon, or to the charge of possessing an illegal weapon, … ,or that said person has avalid permit and license for possession of such weapon.
A "valid permit and license" is your NFA Stamp. Take silencers off the registry and you can't get a NFA stamp. Without a stamp you don't have the affirmative defense.