Hi guys,
A couple of months ago, I equipped and tuned this AR with an Altaros regulator:
http://sport.tweedehands.net/schietsport/unieke-daystate-air-ranger-25.html It is getting about 57 shots from a 250bar fill before velocity drops...... at 75 joules (57ft/lbs) with king heavies

Without any other adjustments, just fitting the regulator it was doing only 25 shots at 57 ft/lbs.........
From 25 to 57 shots with the same energy brought a big smile on the owners face

(and mine too

)
A flat shotstring is easily achieved with a regulator, but to tune it for a high shotcount is the big challenge.
I made a lighter hammer (stainless steel hammer with delrin spring housing) and fitted the strongest spring he had, but with very little pre-tension in released state.
With other words, there is almost no pressure on the valve stem when the hammer is uncocked.
This almost makes it a free floating hammer, like the FX guns have.
An other way is to try a lot of hammer springs with different lengths and wire diameters. Make sure the tension on the valve stem is as low as possible in uncocked position to prevent air waste.
Good luck
Gijs