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.
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.
Greek-made HK91 copy with optional PSG-1 grip, bipod and 30-round magazine.
The HK91 is rather valuable in the United States firearm market since it was banned from further importation by executive order in 1989. Only 48,817 HK91s were imported into the U.S. prior to 1989. The retail price for an HK91 in the late 1970s was roughly $380 for the standard A2 models and $50 more for the A3 version. Prior to 1979, H&K did limited production runs of HK91s with polygonal rifle barrels. These were only $10 more than their standard counterparts. Today, original HK91s often fetch over $2000. The early 1974 ‘SACO’ imports that are in good condition, which have the old style “SF” marked grip frame housings, are desirable among H&K collectors. So are the 1988 and 1989 “Chantilly” models, which have the same satin semi-gloss black finish as the later HK SR9s.
Licensed copies of the G3 and HK-91 were produced in Greece by Hellenic Arms Industry or “EBO”, using factory tooling purchased from Heckler & Koch. A small number of these HK-91 clones, which are functionally and aesthetically identical to the German-made rifles, were imported into America by Springfield Armory, Inc. and sold under the designation SAR-8. These rifles, which ceased being imported in 1994, are not to be confused with later Springfield-made SAR-8 model rifles which feature cast aluminum receivers and are considered of markedly lower quality, being valued at far less than the original Greek models.