Have you heard anyone reporting the accuracy of the .25 GTO lead free pellets and what is the ideal FPS to shoot those? Those pellets are cool but a bit pricey. I am still intrigued as some of reported that in the .22 caliber they felt that it was slightly more accurate with no issues on jamming; but I have not seen anyone providing feedback on results with the .25?That makes sense because the cross section area of a .25 is about 30% more than that of a .22. The current "happy point" (flattest shot string) of the .22 GK1 shooting 22 gr pellets is about 870 FPS. 870:700 is about 1.24, roughly agreeing with the 30% increase of cross section area of the barrel. The power wheel setting is about 1.75 rev. CCW from the min position, also roughly agrees with @killraven4334 's setting. My shot string is from a 325 bar fill, shooting down to about 210 bars for one clip (19 shots).
The interesting part is that 870 FPS is also the "happy point" for light pellets like GTOs and HN FTTGs. The power wheel setting is about 0.75 rev. CCW from min for the lighter pellets. The shot count does increase with lighter pellets.
All of these observations are consistent with the theory that it takes a flow of about 400 cubic inch per second (870 FPS * 12 in/ft * 0.11 in^2 * 3.14) to have any significant effect on the closing valve actuating faster. It'll be interesting when the .177 version is available because this calculation puts the MV to above the speed of sound in order for a .177 to achieve the same flow rate. Huben can probably tune a few variables for the .177 version to have a flat shot string centered around 950 FPS.
I have also observed the first shot being slower, but not that much these days. If projectiles are wet-lubed, that can partially explain it because the lube may get viscous as it dries in the barrel. I dry lube my pellets using a PTFE spray where the solvent/carrier dries before I load the pellets.
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