I have found that if you use a manufacturers replacement spring, that you clean and polish well (Dremils are good for this) then make sure that the top hat is free to move and a good re-lube then in most cases it always makes them shoot better. I sometimes make a plastic spring guide from a pop bottle and ocasionally I will add a washer or two at the front of the spring behind the piston. However any thing over 11fps is OK. Also because it's not a radical tune the gun usually shoots as smothly if not more so than before.
Rgds
Big Si
Lo there do I see my father. Lo there do I see my mother, and my sisters and my brothers. Lo do I see the line of my people back to its beginning. Lo they do call to me and bid me take my place among them, in the Halls of Valhalla, where the brave may live forever.
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