BSA Mercury

[hawkdriver]

Mines an early one, never could hit much with it, i put it down to the pin breach design, i keep meaning to strip n service it but the things a got so much preload i doubt i'd get it back together, can the spring be shortened on these to reduce preload to ideally zero, mines .22, and a early ZA number, early 70's i think, any ideas on making these smoother / accurate, mine used to make a horrid twang, thanks