 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.