Piston Sleeves ?

[Cedric 132]

Is it a good idea to try and fit a piston sleeve to my new HW99S .177 ?

 

It's still a bit 'twangy' even after a good polish of the internals.

 

If so, what would you recommend, metal; ptfe or what ?

[thursodog 353]

Engineering shim Cedric.

Can't get a link up for you but type in shim to ebay.

.006" is ideal for a piston liner.

 

Chris

[Lancashire Hunter 22]

Yeah i piston sleeve will help also a new spring guide and top hat as the standard ones have a bit of play in them between the spring and top hat and spring guide plus i think the standard top hats are metal aswell it does effect them.

But to start with the piston sleece you can make one out of either a coke bottle or if your careful you could use a beer can cut top and bottom then cut one side down the middle wrap around the spring and push it in i reccomend a plastic bottle though.

[Cedric 132]

Thanks for the info.

 

That raises another question! When I dismantled the rifle to clean and polish the spring, piston etc. I saw the spring guide was plastic (?delrin) with a metal washer, there did not appear to be any 'top hat' on the front end of the spring. I just assumed there was not one fitted. Could it be missing? It's a new rifle.

[barrywhite 282]

A tight spring guide ,with a little bit of grease on spring ,so the gun dosent diesel .The sleeving option is a bit low tek ,my opinion only ,it does stop twang but so does a tight spring guide .

[Cedric 132]

A parts diagram I found did not show a 'top hat'. I'm thinking of fitting one though, plus a piston sleeve. Chrono'd at my RFD today and it's only putting out 9 1/2 fp's with average fps of 725 but pretty consistant, only 11lbs deviation. Info from Hull Cartridge Co. is to try a top hat of 3mm and see what happens.

[barrywhite 282]

if your gun is still new the piston seal may still be tight fit. did you use light pellets with chrono

Edited May 19, 2014 by barrywhite

[Cedric 132]

AA Dialblo fields, 8.4 gr.

[PJWmids 35]

I fitted a Welsh willy to my 99 and it sorted the twang out and I played around with the power washers and it's at 11.4 fps. I put in the piston sleeve but took it out later as I didn't like it in. The top hat and spring guide sort out the twang.

[davyt63 1,839]

Thanks for the info.

 

That raises another question! When I dismantled the rifle to clean and polish the spring, piston etc. I saw the spring guide was plastic (?delrin) with a metal washer, there did not appear to be any 'top hat' on the front end of the spring. I just assumed there was not one fitted. Could it be missing? It's a new rifle.

 

hi Cedric

the top hat may still be in the piston,squirt some degreaser in there and give it a tap a few times ,and see if it falls out.

some times they can get caught up in a load of grease and stay there,if they are loose fitted to the spring.

[Cedric 132]

Davey, I checked that, not one there. Everything has been de greased and polished and I've made a 'top hat' to try it plus a spacing washer ( maybe overdone it). Also made and fitted a piston sleeve, used the base of a cooked meat tray from the supermarket. The plastic is solid and strong and moulds with a little heat ( to form the retaining tabs).

 

Now all I have to do is search my workshop floor for the small spacing block that fits under the stock retaining screw and I can re-assemble and try it out !!

[Cedric 132]

Quick update, re-assembled the rifle would not cock, the spacing washer must have been too much, took it out and now it cocks with the top hat in, will chrono it tomorrow. I had to make a new safety spring, mine disappeared - used a spring out of a pen, worked fine.