The plain language of the 1968 act would prohibit these imports, yet the A.T.F. appears to be relying instead on standards in the 1994 assault weapons ban to approve them. The 1994 law banned the domestic manufacture, sale and possession of 19 kinds of assault weapons and barred the manufacture and sale of other semiautomatics with certain military characteristics such as bayonet mounts, grenade launchers and flash suppressors.