My impact which was in .177 when new. It did not shoot that good, even the chrony numbers was good. 10 grains JSB was shooting around 880fps setting 5 on powerwheel. Reg was from factory set at aprox 85-90 bar. Setting on "max" it was doing 990fps. 880 was the slowest I could shoot them as the powerwheel had all slack from setting 4 and down. I later increased the hammerspring to check the true maxspeed which was 990. JSB 8 grains was doing 940, and was already wasting air. It was not until I lowered the velocity with the valve adjuster, that the accuracy increased. I later increased the reg to 115 bar, and adjusted the hammer wheel. In the end it did shoot better on my setting on 880-900 than from factory.
I think Ernest Rowe said somewhere in a interview, that the adjustable guns has some kind of a standard tune, as the customers will adjust them anyway. Guns like impact, and crown are probably not harmonically tuned from the factory, but are probably just shoot and adjusted over a chrony to get low ES and efficiency, on "standard" speeds, on the highest setting on the wheel. It kind of make sence, as when the reg brakes in, the set pressure might end up 5-10 bar higher (lower?) than set from factory. Combinning that with that customers will adjust them anyway, spending man hours tuning the gun to perfection at factory is probably wasted time anyway. The factory doeas not know what pellet the owner will use either (8 or 10 grains?), so if they had to adjust it for perfection, they had to choose. Some resellers does tune them on theire own, before shiping them to customers.
