so, on my rwa upper (not sure if the same as a wk180 upper) there is about 1" of material on the front of the receiver. ie, it's about 1" from the base of the barrel mount to the inside face where the bolt carrier stops.
also, the short stroke piston only travels about 1".
so, why not design a captured +/- 1" piston that just sits in the receiver? use a standard AR gas block and a shortened gas tube to get gas to it. thinking a threaded fitting to connect the gas tube and get the piston out for cleaning. you could drill a hole in the side of the receiver to vent at end of travel. chromed piston and perhaps an insert in the aluminum receiver to reduce wear.
less weight, less to break. perhaps use pencil barrels again, at whatever gas length you like.
also, the short stroke piston only travels about 1".
so, why not design a captured +/- 1" piston that just sits in the receiver? use a standard AR gas block and a shortened gas tube to get gas to it. thinking a threaded fitting to connect the gas tube and get the piston out for cleaning. you could drill a hole in the side of the receiver to vent at end of travel. chromed piston and perhaps an insert in the aluminum receiver to reduce wear.
less weight, less to break. perhaps use pencil barrels again, at whatever gas length you like.




















































