Distributors often get these guns and re-finish them to increase the salability of them and that's probably what these are. I know one that routinely adds aftermarket grips, touches up bluing, and does some polishing on stainless, so it's highly likely the matte finish was done there.
Incidentally, I haven't had good luck with Smith surplus revolvers like these. My feeling is (and I would love to believe differently) that from the 2 I owned, they are pretty much at the end of their useful lifespan. The actions of both guns had seen many armouring attempts, and I think were finally just junked due to unreliability. Some minor gunsmithing at my expense fixed one well enough, but it never was accurate, and the other never could be fixed.
I also wonder if these distributors aren't slapping these guns together out of parts, as mine seemed way less accurate and functional than they ought to be, despite having a great finish.