In 1942, the SS devised a plan to rent out concentration camp labor to companies in the German armaments industry. Several different rifle production lines were set up to make use of this source of cheap labor, and the one we are looking at today is Steyr’s plant at the Gusen camp (a subsidiary of Mauthausen). A rifle production line was established there in March 1943, and in June 1943 Stern signed a contract to supply the SS directly with 10,000 K98k rifles per month. This production was outside the standard Wehrmacht inspection protocol, and the rifles are recognizable as SS contract guns by having receiver codes of bnz43, bnz44, or bnz4 in addition to:

- Lack of WaA inspection stamps
- No letter suffix on serial numbers
- Serial numbers only on receiver, bolt, safety, trigger guard, stock, and hand guard (later also floor plate)

The Gusen production line was not always able to produce as many parts as needed for the SS contract, especially receivers early on. To complete the necessary rifles, parts were brought in from other Steyr factories (in particular the plant in Radom, Poland). These supplemental outside parts were marked with single “S” runes to indicate their special destination, and to bypass regular Wehrmacht inspection. Thus the rune-marked receivers are actually the non-camp-produced ones, contrary to general assumption.

At any rate, this special SS contract lasted until 1944, when it was cancelled and Gusen production rolled into the standard Wehrmacht logistics program. In September 1944 the Soviets occupied Radom, and the loss of the rifle factory there forced the Wehrmacht to find a replacement source of arms. Before that Gusen parts were also used to supplement other factories, but after October 1944 its role fundamentally changed.