Short Barreled Rifle (SBR) is a rifle with a barrel shorter than 16 inches. An SBR is less effective than a rifle but more effective than a handgun for self-defense. It is also more efficient for traversing close quarters to clear a threat from your place of residence such as a burglar, etc.
Supressors are used mostly for safety purposes.They reduce the sound of each shot, greatly reducing the possible damage to the operator's hearing. In close quarters this also benefits those in close proximity. Supressors also reduce the amount of felt recoil, eliminating muzzle flip and increasing accuracy. Its more considerate for neighbors while on private property as well.
The need to register a Suppressor or SBR (and Short Barreled Shotgun) is unjustified and the requirement should be removed