Hw35

[tuck1]

That's a kind offer, thank you. Pm sent.

[CapitalBee]

BTW a few people recommended using a biro spring to replace a lost safety spring...

[tuck1]

So, thanks to a very kind offer from a member, I'm now the proud owner of a new stock screw, and a combro, so yesterday commenced testing with my HW. And my worse fears regarding the power were confirmed, I'm getting 4 ft lbs with superdome, and similar with some other pointed pellets I happened to have lying around. This rifle fettling business is more difficult than I thought! The rifle still takes considerable effort to cock, and has a couple of inches of preload, so my thinking now is

Do I have a German spec low power version, is there any way I can check this?

Do I have a leaky cylinder with the brazing issue?

The piston is still fairly tight in the cylinder, it moves up and down, but takes a little bit of pressure, I'm wondering if this is robbing power, but I've got a feeling that it isn't robbing that much. Everything is well lubed up.

I have this feeling of dread that I'm going to be tangling with those shim washers again very shortly!

Any ideas would be very welcome, thanks in advance.

[CapitalBee]

I'd do the leaky breech fix before anything else now. I've done it two older HW35's with good effect.
For the breech shims, I use a tapered punch and once you've got the shims roughly aligned, push the tapered punch through the hole - it pulls the shims into alignment.

[tuck1]

^fantastic info, thank you, that's a great plan. (And thanks for the idea for the pen spring too).

What's recommended for the breech fix, JB weld, some kind of Loctite?

[CapitalBee]

I used Loctite 271, though I have heard of JB weld being used. Clean prep' of the cylinder was important and I applied the loctite with a drinking straw, then tried to pump it into the voids with the piston (whilst avoiding getting the piston and seal into contact with the loctite. I blocked off the transfer port with a rubber bung and cleaned the excess loctite out of the cylinder after an overnight stand on the radiator (in the vertical)

[TonyL]

I have this feeling of dread that I'm going to be tangling with those shim washers again very shortly!

Any ideas would be very welcome, thanks in advance.

DON'T DREAD THE SHIMS!!

Try this....

Offer barrel up to breech jaws (and cocking lever in position, obviously).

With the action on your legs, left hand side up ( as you're shooting it) give the barrel a slight wiggle whilst offering the shim up - by feel you'll know when it's right, and the shim will slip in. Push the bolt right through to the other side, but not quite enough so it'd stop the right hand side shim sliding in. Flip the action over. Repeat the barrel wiggle, that shim should also slide in. Ensure central, push the bolt right up, engage threads, job done.

I normally use a cocktail stick / small diameter wooden drinks stirrer to pull the shim into alignment.

Hope this helps a little.

[tuck1]

Well I've plucked up the courage to have a go at sealing it up this evening, all I had was loctite 243 so here's hoping it does the job. As suggested, the cylinder is sat upright, TP plugged, and the piston is in place keeping some kind of pressure/vacuum I hope, anyway the plan is to leave it tonight and reassemble tomorrow, using the shim washer anti swear technique as described above. Thanks to all who are inspiring me to have a go, I'll keep you posted..

[tuck1]

Well, I awoke this morning full of optimism and enthusiasm, and positively bounced into the garage. I was, however surprised to find that some of the loctite was still liquid, maybe the cylinder was not anaerobic enough, or maybe I was just cutting corners and using the wrong stuff. Anyway, I cleaned it out, and reassembled. I'm getting quicker at this, and a combination of the methods above certainly assisted in preserving my mental wellbeing. So, combro on, and fire a string......and I received a consistent 4 ft lbs! Bugger. Back to the drawing board......

[I. J.]

The piston is still fairly tight in the cylinder, it moves up and down, but takes a little bit of pressure, I'm wondering if this is robbing power, but I've got a feeling that it isn't robbing that much. Everything is well lubed up.

I have this feeling of dread that I'm going to be tangling with those shim washers again very shortly!

I would suggest that the piston seal is too tight and needs sizing.

Do the shims one at a time. I use a grubby Philips screw driver and use the pivot bolt to push it out once they are aligned. Once you have done it 50 or 60 times it becomes a doddle.

HTH
Ian

[Amac]

You are clearly getting frustrated with your HW35 dalliance! However, don't give up. When you finally have a gun that shoots as smooth as a well fettled HW 35 does, it will have been worth all of the pain. My own 35 E ticks over @ 10.5 with Hobby pellets in .22. Your gun clearly has some way to go yet, and Ian's recommendation concerning the tight piston seal would also be my own next port of call I reckon.
Let us all know how you get on and good luck!
Andy

[davymole]

watching this post with interest if it was a german low powered rifle it would have the <> on the barrel the spring looks the same but thats as far as it goes.You have tried the leaky breach.sized the piston seal.replaced the breech seal removed all wiggle from the action/barrel and its still only 4ft/lbs .I would strip again and look at every item rebuild and relube lightly I have rebuilt them with no or very little preload even had one at 17ft/lbs with that rifle stripped ,cleaned just compressed a coil it was even higher bought another spring soon OK, why just fitted the same no 4 spring soon sold this one on

[tuck1]

I can tell you are sensing my frustration! However, mixed in with that, I'm thoroughly enjoying the project. As a lad, I couldn't afford a weirhauch, or indeed any air rifle, and looked on those that could with extreme jealousy.i managed to borrow a friends ASI magnum at one point, which looking back was probably a horrible gun, but felt on top of the world. I have always looked on the German guns with a certain amount of respect, so when I got hold of this one I was really looking forward to owning a prestige weapon, even though it was as an adult!

I never really expected to see this gun again, and had written it off, so really I'm quite happy to put a few quid into it to get it shooting, as I feel that it owes me nothing really.

I'm tempted to get hold of a synthetic piston seal and adaptor head, then chrono it to eliminate it from my list of things that could be wrong. I guess I could always sell it on later if I solve the problem and return to the leather seal. In the interim, I'll order some loctite 271 and try to do the job again.

Hey ho, the trials and tribulations of airgun tinkering. This could become addictive!

Thank you all, I really appreciate your continued input and advice.

Ps exactly how easy should it be to push the piston down the cylinder?

[Garvin]

Ps exactly how easy should it be to push the piston down the cylinder?

As I understand it, the piston should just fall through the cylinder under its own weight (ie with gravity alone), and stop when you put a finger over the transfer port. The piston being too tight in the cyinder could be responsible for some or all of the power loss in my experience too. Good luck!

[tuck1]

Just a quickie for the engineers amongst you

Is it feasible to pressure test the cylinder in a bath of water to check for leaks? Or does the air leak from the cylinder into the "cavity" and not generally show up on the outside?

Ta

Ps you were all right - first rule of airgun tuning- get a chrono so you know what the starting point is!