Its not a dumb question, best I can say is I don't know for sure. You can make some guesses - at this point in time I believe the SS Gew conversions were done by commercial firms in the Suhl region for the SS. Using leftover military parts for commercial hunting rifles was pretty widespread, and it was normal course to remove the military markings for these commercial rifles, either to obfuscate the military ownership connection or for cosmetic purposes. I suppose these 2 reasons are possible for the SS guns as well, and some of the SS rifles were from the hidden stockpiles of the Weimar era. If you study the political situation surrounding the SS you get an idea that not too many other people were keen on the armament of the SS, and any "ammo" the Heer could use to undermine the SS was probably fair game. Although, I'm not suggesting the scrubbing was a defensive measure against the Army pressuring the SS, that was done on the political front.
We know the recievers are WW1 receivers, we see slight evidence either under the woodline or ghost images of inspections and proofing that isn't always completely removed. So it isn't as if these were made using new components.