Hw35

[tuck1]

Good afternoon

I have spent several days searching for the answer to this one, despite finding a wealthy of other info I can't quite seem to nail this one.

Some years ago I bought, from a gunshop, a very well used and unloved HW35. The breech seal was in a bad way and the woodwork, and metalwork was poor too. The day after I got it home, a farmer friend borrowed it, so I never shot it. It has recently returned to me, and with the assistance of numerous posts on her, I have stripped and dismantled it. It is a leather piston seal version, single sided safety. The serial number under the barrel doesn't seem to match any dates I have seen, it's 721757, my guess is that it's late 70's? Any thoughts?

Anyway, now it's in pieces I've found it has a square section spring which was under considerable preload. It shot horribly, low power, high recoil, spring twang, very difficult to cock.I don't have access to a chrono (I know this is something that I'll need to address on re assembly) but the power was well down. I've replaced the breech seal, rejuvenated the piston seal in SM 50, and swabbed out the chamber with meths. It has the original spring guide. I've ordered a original mainspring from Chambers, which has arrived, and thus lies my main question...

The replacement, new Chambers spring is longer than the one which has come out (which I'm guessing is an Ox.) the old spring is 22.5cm long, and 26 coils. The new one is 24cm and 27 coils, so under even more preload. Am I right in thinking that the new spring is not a direct fit, and will need cropping/ refinishing first, or should I be trying it first, squeezing it in and then chrono and reduce by degrees until satisfied? This would be a problem as I will be taking it to a gunshop to chrono it.
Obviously being a hw35, I am more interested in a sweet shooting gun than high power levels.
This is my first attempt at airgun stripping and maintainence, and what an enjoyable project it has been so far. I can't wait to get it back together when my moly grease arrives.

Many thanks, in advance for your wisdom.

Adrian

[junglie]

My '77 35e makes 11+ ft/lbs on it's original standard spring & leather washer(rejuvenated with hempseed oil), it has very little preload ,maybe half an inch from memory. It's the only springer I own I've rebuilt without a spring compressor!

[tuck1]

Thank you. From memory can you remember how long your spring is?

[Heavy Roller]

Are you certain that there are no pre-load washers inside the piston?

[tuck1]

There doesn't appear to be, the spring inserts 9.5 cm into the piston.

[davymole]

you are right with the date being 1979,I just replaced a 35 with a weihrauch spring old new stock with 28 coils and round not square and a new leather washer and piston its at 11ft/lbs this had no preload at all .has settled down.the recommended Ox is a number 4 .this still uses the original spring guide.

[JLB]

The spring you have been sent appears to be the new Weihrauch standard spring fitted to most of their full power guns. I would fit it & then have it chronoed.

John

[tuck1]

Thank you. I have taken 3 coils off the spring, which still gives over an inch of preload, and put it back together. It's still quite difficult to cock, but easier than it was. I haven't shot it yet, and I suspect I'll be cutting the spring down some more yet. I have also managed to lose the safety catch spring along the way, so I'll need to order one, along with a front trigger guard bolt which I forgot about.

I hope after all this is doesn't suffer from the brazing issue.

[vincy]

i have a hw 35 barrel in 22 in a cupboard

[tuck1]

Well I finished up cutting a couple of coils of f the spring, and reassembling the gun with some difficulty as there was still a couple of inches of preload. Gave the spring and piston a very light smear of grease, almost invisible. The gun was easier to cock, but still twangy, and after over 100 pellets it still won't group, and seems to be getting progressively more difficult to cock.more grease required? I am definitely thinking that I need a chrono of my own now, to get to the bottom of this, is there anything else I may be missing? Spring still too long?
I'd be grateful for your thoughts.

[landymick]

What cal is it?
Are you using good pellets?
Is the piston seal in good condition?
Is the barrel tight enough with no droop? & is the breach seal ok?
A bit more moly grease on the spring should help the twang,new guide & top hat kit would be better.Idealy you could do with knowing the power output to see any improvements made.

[tuck1]

Thank you Mick. It has a new breech seal, and the piston seems ok. Since posting I have stripped it again and re lubed , using a bit more grease. There is still a pronounced twang, but it is cocking more easily again. As for barrel droop, I don't know really how to check, I'm aware that some suffered this issue. I think you are right about the power, there's no point guessing, I need a systematic approach to this, I'll get a chrono. Pellets are decent, and there's no sign of dieseling, it's a .177.

On the up side, I've just stripped lubed and reassembled it in less than an hour, including the swear inducing barrel shims!

[CapitalBee]

I recently rebuilt the exact same model HW35 as you, mine was 1973 vintage. I bought a standard spring and had to cut two coils of to enable me to fit a top hat and spring guide. This got rid of the twang. It also seems to hit a sweet spot with the spring performance as the fpe went up 1fpe after lopping off the coils and fitting the top hat. I believe that HW's of this age didn't have shims originally so could the cocking problem be the gap being too tight between the barrel breech and cylinder?

[tuck1]

That's interesting, thank you. I'll lay my hands on a chrono, stick some more pellets through it, and see where it is power wise. I've also realised that it is missing a trigger guard bolt, which could be the source of my problems. (Shame it's not with the safety catch spring, which has gone into orbit somewhere in my garage.) I'll try to get hold of both, and see how I get on. I've never actually shot a tuned springer, so have no idea what is achievable really. However it is a very enjoyable project, and I'm learning lots. The cocking issue seems to have eased with a dab of grease on the shims and joint.

[greasemonkey]

hi, just a thought,the action retaining bolt that goes through the trigger guard is a 7mm thread ,an odd size.i needed one for my hw35.i got one from the bay intended for a lambretta scooter which i had to modify from a bolt head to a slotted screw head.if you get stuck give me a pm and i will have a root about in the workshop as i believe i bought a packet of three of the odd things..cheers..greasemonkey..