Stripped upper receiver

thingiverse

M4 stripped upper receiver. This is made to hold a V2 gearbox and a rotary hop up chamber. I haven’t tried it with the electric blowback version or the old hop up chamber. For the bolt window I designed another charging adaptor since the original was not working properly and had to dent a bit the metal so it comes to its original position. I can add the lower and the piece for the charging mechanism in the future. The lower needs a bit of adjustment.