Just do it discreetly in your home. Sure it maybe a bit loud when using gas, but I doubt the neighbors would hear it unless the walls are paper thin. Be smart, dont do it near windows and just get a couple pillows, and a blanket and youre good to go. Make a cave like contraption with the blanket and it would absorb most of the shots.
Like others say, treat it like you would a real fire arm. Dont take it out in public without storing it safely etc etc etc. Store it safely when not in use. Simple stuff