Hello. I made my fx crown continuum 25 cal. Power plenum 13-15 cm3 steel with an adjustable valve spring.Hammer 10 g. At 150 bar. max speed with JSB MK II 984 fps and with NSA 33.5 gr. 971 fps. So far, that's enough for me. If you go more than 155 bars, you need 12 g. hammer. I have now...