HW 77 power issue

[Amac]

Just replaced the mainspring on my old .22 HW 77. Used a Vmach one of obvious quality. Now I appreciate that manufacturers are careful of producing springs that can send a gun over the limit, but she is still only putting out 9.3. Question is,how do I preload the spring to increase the power,and with what ?
Thanks, Andy

[ikarma70]

i'd put a few hundred pellets through the gun then retest it before adding washers.

[munchman]

Is the piston seal OK ? Also check the breech seal

[Amac]

Thanks for the feedback chaps. Will check the seals out and give it time to settle down a bit. Andy

[PeteB]

As someone already, give the spring time to settle. Stick 200 or so pellets through it and test again.

However, if the old spring was knackered, I would be suprized if the old piston washer was still serviceable.

[I. J.]

Have you been 'energetic' with the spring grease? If this gets between the piston and cylinder walls it can cause drag and power loss.

ATB
Ian