The visible differences include the removal of the flash suppressor, bayonet lugs, and pistol grip (on the base model) in order to improve the design's acceptance as a sporting rifle.

The SR9-series rifles have unreinforced receivers fitted with iron sights and a semiautomatic-only trigger group.

The barrel has the same bore profile as the PSG1, including polygonal rifling, and lacks a muzzle device.

The 1989 Import Ban, enacted by US President George H. W. Bush, bans from importation all semi-automatic rifles with a folding or telescoping stock, separate pistol grip, bipod, ability to accept a bayonet, grenade launcher, night sights, or flash suppressor.

H&K was also required to put a spot weld over the end cap detent because the ATF considered the hole to be a bayonet lug.

President Bill Clinton halted the importation of all HK SR9s on April 6, 1998 because they could accept a standard capacity magazine.

In 1989, the Bureau of Alcohol, Tobacco and Firearms had not determined what was considered acceptable as to what grips were fitted to the rifles by H&K USA, and the new rules were not set to be "in force" until November 1990.