You can get as good a tune without buttons on the piston, if you do insist on delrin have you thought of Maccari stick on buttons? They do work. The 95 and 80 can be tuned to give a very sweet shot cycle with attention to the cocking slot, piston seal sizing(V-Mach are still the best seals available) guide fit and spring choice. If you have a good compression/reciever tube and the piston id centred by the guides and seal there is no need for buttons IMHO.