Actually, I just tuned mine with a Huma regulator set at 110 BAR, stock hammer spring and a Hill .140" replacement transfer port (no drilling) and got 680-700fps using Crosman HP (14.3 grains) for 15FPE at the muzzle. I got 20 usable shots with a 3000psi fill and 24 shots with a 3400psi...