Hw35 refurb

[mrikirkby]

I Have just started stripping and refurnishing my HW35 and just wondered what peoples thoughts are as far as tuning goes. I don't want massive power just for it to shoot and cock smooth, it already has a synthetic piston seal in it and standard spring I think although it is quite a loose fit around the rear spring guide. I am going to replace breech seal but that's it at the moment, any thoughts on the best way to go chambers, Vmach or B&C ?

[Hsing-ee]

V-Mach or B&C are good, Maccari does a soft-recoil kit as well which might suit your needs, any one of them could do the trick.

Alternatively, you could try a basic tune yourself first and take it from there. Fitting a piston sleeve might make it quieter too.

http://www.airgunbbs.com/forums/showthread.php?t=115108

[coburn]

Have you sized the synthetic seal, it makes quite a difference to the power. Also is the little roller wheel bearing in the cocking arm worn allowing the linkage to score against the cylinder?. Venom used to replace this steel wheel with their own larger plastic wheel which makes for a smoother cocking stroke.

[mrikirkby]

Thanks for reply s, how do I size the the piston seal ? It is a tight fit in the cylinder if that's what you mean ?

Will check the wheel.

[coburn]

I usually clamp a drill in a vice and using a slow speed and very fine wet and dry sand the piston until the seal is a nice sliding fit in the cylinder. Only do it a little at at time and check the fit often.

[Sabo]

Looks like you have one of the early models that originally came with a leather piston seal. Very accurate rifles and a joy to use. Had a few over the years. What about a Bonnie and Clyde kit. Hear they are very good

[mrikirkby]

@ Sabo the piston seal is synthetic it is a loose fit on the piston but very snug in the cylinder ?

[mrikirkby]

started on the stock today, bit more rubbing I think !




Piston and seal ...

[junglie]

that looks like a tr robb ptfe seal to me.

[mrikirkby]

Here is a better picture of the piston seal if you can shed any light on it ?

[premierpistol]

Thats just a standard hw synthetic seal, looks like the later piston to be honest infact they all are the same once the leather seal to synthetic seal conversion is done.

I've had very good results out of 35's with a piston liner made from a drinks bottle and a hw77 titan spring which were cut to length and had the end reformed. I also made the matching tophat and spring guide to suit and it always reduces the felt recoil which makes the 35's a very nice shooting rifle. Dont expect much power but a very comfortable 10+ FPE is more than likely and it'll still shoot nice, I've had them to full power but it ruins the feel IMO

If you are sizing the seal and find it keeps spinning on the piston (as per usual) remove the seal and slip a piece of paper over the seal dovetail and refit, this will hold it on tighter to allow you to lightly size using wet'n'dry 600 grit paper

Best of luck with it

PAUL

[hwvixen]

Its the same pic isn't it..or am my old peepers playing up..?

[mrikirkby]

@Vixen yes sorry mate its not you mince pies playing up it is the same pic i didnt realise i had posted it earlier !

@Premierpistol
1.were does the spring sleeve go outside the spring or inside?

2.Is a top hat just a delrin washer that goes in front of the spring?

3.Yes the seal is a loose fit on the piston but is tight to get in cylinder especially past the threads for trigger block are the chambers seals any good or should i just try and size this one ?

4.I am going to make a delrin rear guide machined to fit the spring so a tophat may be done as well. Is it worth replacing the spring if so what type or should i try shimming the original one ?

Thanks for the help so far its much appreciated as i have never undertook a complete refurbish so its all a bit new to me but I am very handy with my hands and would like to make it my own work rather than just chuck a tune kit it in it .....although they are very good !

[premierpistol]

@Premierpistol
1.were does the spring sleeve go outside the spring or inside?

2.Is a top hat just a delrin washer that goes in front of the spring?

3.Yes the seal is a loose fit on the piston but is tight to get in cylinder especially past the threads for trigger block are the chambers seals any good or should i just try and size this one ?

4.I am going to make a delrin rear guide machined to fit the spring so a tophat may be done as well. Is it worth replacing the spring if so what type or should i try shimming the original one ?

Thanks for the help so far its much appreciated as i have never undertook a complete refurbish so its all a bit new to me but I am very handy with my hands and would like to make it my own work rather than just chuck a tune kit it in it .....although they are very good !

Hi, The spring sleeve should be made to fit inside the piston, it should be as thin as possible to allow the spring some movement, i've seen too many attempts at these with large diameter springs, it wont work as well or indeed at all in some cases. thats the reason i use the smaller diameter HW77 springs. The piston seal should be a slack fit on the piston and just tight enough a fit in the cylinder to create a seal, if it's too tight it will need extra power to propell it forward, this leads to inconsistency and over time, power gains. just try taking a little off the seal you have, all new seals are likely to be even tighter
A top hat is not just a washer but a mini spring guide, it should sit inside the spring by about 3/4" and the washer part of it should be the diameter of the inner of the piston or spring sleeve. if need be the main spring guide should be cropped in length to allow the top hat to be fitted (80mm is the norm for HW rifles, although some standard ones are getting on in the region of 100mm)
Regarding the spring....... If the one you have is of any age.... replace it! there are a few different ones out there so the choice is yours but i much prefer the titan XS range of springs, they tend to need cropping and the end reforming to settle in legal power territory but they are a million times better than the ox springs and as good as some other well know tuners range of springs (as well as cheaper)

HTH PAUL

[ikarma70]

theres a titan spring in my 77 and its coming out in favour of a B&C kit.

i find titan springs too stiff to cock,its very consistent to shoot(more consistent than a pcp) but a proper bugger to cock.