It's worth the effort to borrow a chronograph and shoot a string of shots from max pressure downwards to see where velocity changes. Mine shoots slightly lower velocity at max fill (say roughly 3000psi), then reaches maximum velocity at say 2800 psi, then holds that velocity more or less until it hits 2200 psi. So it may have a sweet spot where it shoots best. Mine is unregulated, and that is why it behaves that way. Highest pressure provides more resistance to the hammer opening the valve as fully, and lower pressures allow the valve to open further, allowing more air in, thus boosting velocity despite pressure drop.