The Disco hammer is identical to the 22XX hammer except that it has a cutout milled into the top front to miss that tiny 4-48 breech screw.... Crosman moved that screw back (about 7/16" IIRC) so that the floor of the loading port is smooth and that resulted in the hammer change.... It is about 3 gr. (5%) lighter, so no significant difference in performance.... If you use a 22XX breech with a Disco valve (and use the forward screw location) you have to machine a small recess in the back of the valve to miss the screw.... That valve is done that way, you can see it in the photos behind the transfer port.... so it will fit either tube/breech/hammer....

The tank is very rigid, I don't think it needs a band to locate it.... It has more clearance than the one on my QB, because this block I made the offset greater in case I ever wanted to use CO2.... Even the one on the QB (which has only about 1mm clearance) never clinks against the main tube....

Bob