HW77 Tuning

[tinbum]

OK thanks for that
I will get a new set of guides for the new spring.
Having just been made redundant I will have to wait until I secure new employment.
Perhaps you could PM me with the price of the required delrin guides.**

Cheers John.

** Other makes are available!

[Stormdancer]

** Other makes are available!

I didn't mean to imply you were advertising

[TonyL]

Yep, as the Tinster says, the standard spring is longer and gives a softer feel to the firing cycle.

When funds allow, send your spring to him and get him to make the guide and top hat for your spring for a bespoke fit.

Also check the piston and breech seals; these make the power very easily, especially in .22.

[Phil Russell]

Reading this reminded me of the time I fettled a 'project 77' a few years ago. I fitted a new spring (not a HW one) and guide ... the spring had a lot of preload and was a b****r to fit and just about coil bound with no preload washers at all. The result was disappointing at c. 10. So I bit the bullet, as it were, and removed said spring and with heart in mouth removed a couple of coils. The spring was easier to fit and the power increased to c.11. Another coil was added to the bin and I ended up with a rifle running nicely at c. 11.5. This was in .177 Memory fails me and I may have missed a spring shortening stage as I now think that at one point I went OTT ... but whatever, to get the rifle shooting nicely I had to remove coils.
So, while I am not suggesting your rifle may be oversprung, it is worth considering.

Cheers, Phil

[dtdukok]

Sorry for ancient thread revival but I have been trawling through posts looking for how I might get the power up on an old 77 that has just had a TBT kit dropped in...

It has also had new piston and breach seals, has both the power washers fitted and is still only giving me a tad under 11 fp with the pellets it liked best (actually some Game match diablos oddly enough).

Any heavier pellets and the power drops off to about 10 fp. The spring from Nicks kit is HW and gives a good 2.5” preload - thank God for the sash clamp.

Everything has been polished up nicely and lightly lubed in the right places with a little bumslide.

Not sure what to try next. Any suggestions gents?

Thanks,

Darren

[Scubashot]

Has the new piston seal had an opportunity to bed in?
After fitting a V Mach kit (including a new spring and seal) to my 1987 HW77 0.22" rifle the power was way down, even with all the preload washers installed.
As the seal bedded in the power just kept climbing. I had to remove all of the preload washers and collapse a coil of the spring to keep it legal. Even now I have to keep an eye on it and have had to reduce the thickness of the top hat to fine tune the power level.

[Phil Russell]

I wonder if the rifle is over sprung. Until you experience this for yourself it is difficult to imagine: a too strong a spring can actually result in a decrease in power. Certainly the amount of preload you have ... and I assume by preload you are referring to the length of spring sticking out of the cylinder before you try to put the trigger block back in, is quite a lot. My 77k runs at about 1cm and it is no effort to fit the back block.
Can you try removing all preload (power) washers and see where you get to? This may tell you a lot.
Cheers, Phil

[madcarlos]

Has the new piston seal had an opportunity to bed in?
After fitting a V Mach kit (including a new spring and seal) to my 1987 HW77 0.22" rifle the power was way down, even with all the preload washers installed.
As the seal bedded in the power just kept climbing. I had to remove all of the preload washers and collapse a coil of the spring to keep it legal. Even now I have to keep an eye on it and have had to reduce the thickness of the top hat to fine tune the power level.

I had the same as you with my 177 77k, Had to remove all the washers in the end but lucky enough its settled to about 11.2