Mauser used forced labour (or rather 'Arbeitseinsatz') at their plant, just like any other large manufacturing company in Germany did.

Mauser was lucky in that the people under their supervision were treated rather well on a whole. There was a major difference in the treatment of the French and Dutch workers and the Russian and Polish ones, for example. The Dutch and French were relatively free, housed in barracks without much barbed wire. The Russians were well guarded and the Polish (mostly women) were somewhere inbetween.

August Weiss kept a correspondence with many former foreign workers after the war and several reunions were organized in the later years of the last century. This indicates that those under his responsibility were treated well.

Forced labor was an issue (and a grim one) at other Quandt group companies. One of the worst examples was that of AFA / Varta where many people died of lead poisoning and constant abuse. The companies got away with it, because they had 'lease contracts' with the SS. If anything went wrong, they could blame the SS instead and the SS didn't care anyway.

I had the chance to investigate a trial report of a Polish women who had worked as a forced laborer for DWM in Berlin. DWM was acquitted because they had treated their forced laborers like their own workers. (which should be taken with a grain of salt. The forced laborers had no protective gear, nor the opportunity to get or purchase them. They were badly fed in their camps and often abused. But since this happened 'outside of work hours', DWM was not to blame....).

It was truly a black page in the history of German engineering and anyone trying to make an extra buck on this should be ashamed of himself.

When I used to get most of my stuff from vets or families I heard some pretty outrageous stuff that they had firmly come to believe.
I always considered it best to leave things alone.

When in doubt, Throw it out!!