The 1989 Import Ban, enacted by 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. The HK91, HK93 and HK94 models were all on the import ban list. At the time of the ban, about 130 or so HK91s had already been delivered to the U.S. but had not yet cleared customs. H&K complied with the ban by renaming those HK91s as HK911 (basically stamping another "1" after the name) and adding a Bell-Carlson thumbhole stock. 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. This prevented addition of the bayonet. The HK911 did have the standard HK91 threaded barrel but this was covered by a pinned thread hider/cover.