The Century Arms Inc. C93 Sporter is a semi-auto rifle that fires the .223/5.56 round.
It is not entirely clear why Heckler & Koch re-designated the HK43 as the HK93 later in 1974. Part of the reason could have been to change the public’s perception of the rifle from a paramilitary-type weapon to a semi-automatic sporting rifle, which is indicatd by the “9″. After 1975, Heckler & Koch took over their own U.S. importation, which might have prompted the change in name to HK93. In any case, the HK43 and the HK93 are pretty much identical and all the parts are interchangeable.
The major difference between the HK43 and the HK93 is that the HK93s came with 16.125-inch barrels (17.5 inches of overall length with an attached flash suppressor). Moreover, the barrels were threaded, as opposed to the HK43 barrels which had splines, so that the flash suppressors could be screwed on and welded.
Up until around 1980, the HK93s came with buffered bolt carriers and an all plastic A2 stock just like the HK43s had. The stock had a urethane insert in the back for the buffer on bolt carrier to strike during recoil. After 1980, H&K switched to the non-buffered bolt carriers.
There were only 52 HK93s produced 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 HK43 receivers, the end result was “19/74″. For the 1975 models, they stamped the year without the “/” in the middle.