All of the versions that I have seen that have brown plastic are German occupation made guns (mine has clear acrylic grips with some sort silver foil backing).
Many (not all) German made guns were simplified:
Pre-war production style:
I am not sure of the year of introduction. My conclusion (which maybe very wrong) is that the pistols made for the Polish Army had black grips. Since Vonboe great image is for pre-war Polish Army weapons I thought I would help. (and if I didn't reread my post before posting it would be very clear I needed an editor)
It may seem like nitpicking (and it is to some degree) but with such small images I want few who know not to see it and think 'that's wrong' and the rest of the people to form the correct ideas about them.
Vonboe has influenced me on the correct color of Swedish tanks. So he is responsible for how I look at B&W photos of them. When I see HOI IV 'ministers' already in the wrong color uniform (black when it should be brown), I wonder how many other things that I don't know that are wrong that will miss-educate me & others. I know most artist want to make the best looking image and that is a good goal. When dealing with historic images it should be secondary.
I
hate colorized films that have most everything the wrong color and when you compare them to real period color films there is a world of difference.