were date stamped "1/74". United States Importers Golden State Arms Co., Santa Fe Division Pasadena, CA — From 1962 to 1966. Security Arms Company (SACO) Arlington, VA — From 1974 to 1979. Heckler & Koch Arlington, VA — Took over the US import business themselves in 1980 HK91 Variants There are four models of the HK91: HK91A2: Fixed stock and semi-auto "SE" or "0-1" trigger group. HK91A3: Retractable 1-position stock and semi-auto "SE" or "0-1" trigger group. HK91A4: Fixed stock, semi-auto "SE" or "0-1" trigger group and Select Polygonal Bore. HK91A5: Retractable 1-position stock, semi-auto "SE" or "0-1" trigger group and Select Polygonal Bore. There were only 50 HK91s imported in 1974. For these, H&K dropped the month from the date code and replaced it with the number "19" in order to completely spell out the year of manufacture. Since they were built on surplus HK41 receivers, the end result was "19/74". For the 1975 models, they stamped the year without the "/" in the middle. The reasons why Heckler & Koch renamed the HK41 in 1974 are unclear. Part of their reasoning could have been that they wanted to change the perception of the rifle as being a semi-automatic sporting rifle instead of a paramilitary rifle. Furthermore, gun laws that were adopted in West Germany around that time prohibited the civilian ownership of paramilitary rifles. (As a side note, HK41s that were sold in West Germany came without flash suppressors because they were prohibited under the West German gun laws). As a result, Heckler & Koch modified the weapon with a plate welded inside the receiver to prevent the mounting of a full-auto "SEF" fire control group and re-designated the rifle as the Heckler & Koch HK91. Late pattern HK41s and HK91s are virtually identical in appearance (except for the receiver markings and the retaining hole of the cocking tube end cap) and all their parts are interchangeable. The last few HK91s that were delivered to the U.S. in 1989 were blocked by customs after President George H. W. Bush issued an Executive Order banning the importation of "non-sporting" rifles. These were slightly modified, to remove "non-sporting" features like the flash suppressor, and the receivers re-stamped as the HK911, forming a transitional model between the HK91 and the HK SR9. The HK91 is rather valuable in the United States firearm market since it was banned from further importation by