if the valve spring is too heavy
The trade off of a lighter valve spring being that eventually the hammer bounce from the last shot together with the force of the hammer spring will push the valve open and dump all the remaining air.
CO2 is a relatively constant pressure, so I can't imagine you would benefit from the bstaley mod.... You should be able to just use the velocity adjuster to optimize the striker hit to save gas.... Where it might come into play is if you want to dial back the power and go for a self-regulating CO2 setup that will deliver constant velocity over a wide temperature range.... However, that goes hand in hand with less power, AFAIK it won't work if you are struggling to get power from your CO2 setup.... I have a 1750 (2250 with an 18" long .177 barrel) and I can get 130 shots at 500 fps on a single 12 gr. cartridge, and the velocity is nearly constant from 35*F (right out of the fridge) up to 75*F, peaking at about 55-60*F.... The valve is self-regulating just like a PCP as the pressure changes with temperature.... However, the gun had to be detuned from about 650 fps to achieve that....Bob
I too tried the bstaley mod on a Disco with little success.... It is better when detuning a gun that really breathes well..
Bob, I have decided that my FD-PCP is basically going to be a "14.3-grain PCP" while in .22 mode. Reason being, I can access Crosman pellets locally, they provide plenty of energy for small game hunting, the reviews on most of their 14.3-grain pellets are really good and they are very affordable!
You might want to consider experimenting with heavier valve return springs rather than lighter. Peaky shot strings really just mean that dwell is increasing too much relative to the change in pressure per shot. A heavier spring will make dwell less influenced by pressure changes. After all, when you get right down to it, the buffer is just a very stiff return spring with a progressive spring rate.A lighter hammer might help some too.