Bedding In Piston Seal

[Nathan1991 25]

Good morning fellow shooters,

 

I have recently reconditioned, deburred and polished an old hw35. When I got the rifle it came fitted with the standard leather piston seal which was dry and cracked, so I bought a piston head converter and fitted the new ptfe synthetic piston seal, after having it chronod it is a steady 9.5 I was wondering whether this will increase once the seal gets bedded in.

 

I'm looking to get it shooting between 10.8 and 11.5 and ideas on how I could achieve this, I know that the hw35 isn't renowned for its power and are infact difficult to boost.

 

Any advice welcome, cheers guys and all the best.

 

Nathan

[barrywhite 282]

I had a hw 35 a long long time ago from new I did not like the gun .One of the problems I was lead to believe at the time was the inside of the cylinder was rough .So I polished the inside of the cylinder with a piece dowel , a piece of rag rapped on the end and some metal polish .I pushed the dowel in and out of the cylinder with the rag and metal polish until the inside of the cylinder was like a mirror .I did not use a drill with a rotation action the fine scratches with this method would not be so good .this polishing that I did to my hw 35 made the gun shoot a lot smoother and more accurate [ as for power I dont know back then chronos werent available ] . I have since seen a vid by T R ROBB about tuning a spring air gun in this T R Robb uses a honing tool in a drill to polish a cylinder .I think T R Robb methods may be questionable .this polishing I did to my hw 35 100 percent improved the gun but the gun had a leather seal also .this is my experience of one gun that I did this to .

[Nathan1991 25]

Thanks barrywhite, I am looking to get it up by 1.5 - 2 ftlb, and can't for the life of me work it out

[barrywhite 282]

the max power of the gun is governed by the size of the air cylinder .If you put in the strongest spring known to man with the shiniest steel and the slipperiest grease ever you will still only reach a max power .Once I had a spring with a lot of power in a gun that made the gun loose power by shortening the spring the power increased .A to strong spring would be possible in a hw 35 I would think .If the gun has a max power of 11 ft lbs a to strong spring could cause this problem.

[Nathan1991 25]

Hi barrywhite,

 

You may be right as I found the spring in it has loads of preload I literally had to place my whole body weight on it to get it back in. Another problem could occur from the additional 4mm due to the new seal and head adapter, making the overall stroke of the piston 4mm less than it was which in theory could contribute to a decrease in mussel energy, would you agree?

Atb

 

Nathan

[barrywhite 282]

I would have left the leather washer if it was working and bedded in to late now . I had a stupidly powerful spring on a webley omega .It was shooting at 12.5 ft lbs harshly .I thought it would loose a bit of power in time it did not ,so I started to cut bits of the spring the power went up to 15 ft lbs so I kept cutting bits of the spring until the power dropped to 11.5 ft lbs . the gun shoots nice now .So if you have every thing perfect in your gun with a to powerful spring I would say that could be stopping you getting full power .If the gun is harsh to shoot that could be a sign .the 4 mm is not going to help but if every thing is fitting smoothly and not to much grease a weaker spring has to be worth a try .

[Nathan1991 25]

If the spring was over powered would that have an effect on the recoil because it seems like it has a bit much this may be due to the standard spring guide though

[barrywhite 282]

my omega shot ok but under powered so i thought new spring .after the new spring only one pellet would shoot ok from the gun before the new spring lots of pellets shot ok from the gun .The new spring also destroyed I scope in a short time the gun was that harsh to shoot .after shortening the spring the gun was fine if you have an xs spring and not a standard hw spring or similar that may be your problem .I have used 2 xs springs one in a bsa lightning 177 perfect the other in a omega I had to remove maybe 5 coils maybe .

[Nathan1991 25]

Did u use a blowtorch to finish the spring after you reduced it

[barrywhite 282]

also if your breach is not closing properly you could be loosing power there

[barrywhite 282]

no blow torch I feel that will destroy the hardening and tempering of the spring .I just made a steel top hat to hold the spring central .but i would if i cut a spring as a get out put the cut end on the metal spring guide with a washer on the hw

[Nathan1991 25]

Ok cheers mate I will give it a go and see if it improves

[barrywhite 282]

if you cut the spring and put the cut end on the spring guide if the gun dosent cock cock smooth stop .hw may put there cut end in the piston .I have read but that may be with the plastic spring guides.fix your breach first .

[Nathan1991 25]

if you cut the spring and put the cut end on the spring guide if the gun dosent cock cock smooth stop .hw may put there cut end in the piston .I have read but that may be with the plastic spring guides.fix your breach first .

Thanks mate, breech is now fixed solid as a rock it needed 2 things a clear out of the locking mechanism and also it was missing a locking washer from the left side