"broekzwans"
"seahawk1109"thank for every one , i had tried a 18.5 grains for my airgun ,it is 721 FPS , if my HST was not good , i had still use plastic HST ,maybe i should buy a metal's hammer spring adjustment ?
I don't think the metal version gives you more power, the plastic one will wear down pretty fast if you adjust it often. The metal one will keep ticking longer than the rest of the airgun
Try tuning the 18,1 grains to about 890 fps and you'll have a really decent shooter with a pretty hard hitting pellet in .22. For the 21 grains and higher weight pellets I would suggest something which is better suited for these type of pellets, something like the Daystate Air ranger high power in .22 or some other airgun with a plenum that's big enough and a hammer and valve assembly that's strong enough.