What length barrel did you use? I haven't actually measured my barrel yet but I read somewhere that it is 450mm.
As for German kit, I am sporting some surplus flecktarn cammo, but I don't have any vintage style gear yet. If I can find some magazines somewhere (every place I look they seem to be sold out...) I will get reproduction mag pouches for sure. There is a place I can order a flecktarn field cap that looks alright, but I'm not sure reenactors would let me pass with post war gear.