the dia. of the main spring and the number of coils it has. In some case as long as the dia. of the main spring is the same of the orginal main spring a couple of more coils could improve fps in the air gun.
Coils are the loops in the main spring, a couple of coils can improve the fps as long as the main spring is dia. and the length of the main spring is the same of the orginal main spring.
But me, I would go with polishing the outside of the original main spring with wet 1200 grit sand paper, also polishing the ends of the main spring and the main spring's post and lubing it with moly paste.
Another tunning trick is to score the piston's chamber with 40 grit sand paper, to create grooves in the piston's chamber, but this should be done with care.
Over doing will ruin the piston's chamber.
Scoring is done with a rotating motion with a dowel, just enough to create small lines in the piston's chamber to reduce drag and create lube lines. It is only done in the first 70% of the piston's chamber.
But as I said, this should be done with care, overdoing this, will ruin a piston's chamber. Only a experence tunner should do this.
My advice, stick with main spring's tunning/polishing and lubing.
I hope this helps.
Eddie
Posted on Jun 7, 2008, 4:37 AM from IP address 24.139.202.193