>>64086137
I have a couple D60 yes. I do like your air spring idea it also needs a belt drive the gears are loud af. I had a lantac side charging upper on it i got second hand but i wasn’t able to find the bcg that goes with it. I made my own side charging bcg and it worked ok but as it wore in it started dragging a lot and led to issues. I think dirt ingress wasnt helping so i just went back to a normal upper.