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craigfperry · Member

can i increase spring rate by adding a washer?
if so do i fit the washer between the tophat and the spring, between the thrust washer and spring or under the thrust washer?

AirGunEric · Site Admin

Add washers under/behind the tophat against the backside of the piston head. This is usually an experiment with any given gun- some guns you can only add a very small amount of space, others almost inches of space (with that kind of space that could be filled- don't use washers- get some sort of proper spacer manufactured)- it's mostly a trial and error thing from one model of gun to another.

cliffspot · Veteran Member

...to polish them and deburr them. Use stainless if possible. I got a bunch from Ace Hardware on Saturday to tune my Hw77. Had to trim the outside diameter a bit so they fit freely in the piston, you want them to spin unrestricted. I took the piston with me to Ace to check the fit. Deburred and polished them, put some moly grease on BOTH sides then dropped them in the piston first. Make sure you polish the spring ends to glass smooth, don't try and grind them so they are flat, the ends will fail. Polish both sides of the spring guide washer and moly that too. Takes almost all the torque from the shot cycle and makes the gun less hold sensitive IMHO. before you do any of that, invest in a lube kit. Minimum you need moly and tar. Jm sells the stuff, Rich from Mich sells a lube kit with 4 different greases. here you go:
http://www.airguns.citymax.com/catalog/item/251484/4169286.htm
http://home.comcast.net/~peterdragin/index.html/My_Homepage_Files/Page11.html

craigfperry · Member

beautiful, thanks.

cw · Banned

I've found that it varies with each gun. Some guns don't
respond very well to adding weight to the piston assembly.
While adding piston weight to other guns will make them
develope more power, especially when using heavy pellets.

It might be better to add them to the stationary end of the
spring. The only limitation that you will usually run into is
that if you add too many, the piston will not travel far enough
back to engage the sear and will not cock.

CW

cliffspot · Veteran Member

...if you put too many on the spring guide, you effectively shorten the guides usable length! So it is a balancing act of trial and error sometimes. I just use them for rotation bearings to keep the spring free.

cw · Banned

Yeah. it wouldn't be a good idea to put them on the spring guide.
They go on the other side of the spring guide.