HW35 - Aggressive spring noise

[Bazzatron]

Howdy gang,

So I finally, after two attempts and a very legit spring compression setup, I got the HW35 back together and in a state where it fires. The safety engages after priming each shot, it cocks and latches successfully, and it fires - even my rebuilt trigger feels good (not quite competition good, but light enough).

The issue I have is that it is heinously difficult to cock, and it makes frankly awful noises the whole way both to the point of cocking and when drawing the barrel back towards the locked state.

My hypothesis is that the shoe at the end of the cocking arm is riding up and over coils of the spring. I've checked the spring geometry, and it seems a reasonable size for the range I've seen people talk about for stock HW35 spring. I even did the calculation to ensure that the spring wasn't getting fully compressed in the space that I have - and I could probably get away with another coil or two before I bottom out inside the piston.

I checked the serial, and it's a 1975-76 model, still has a leather piston that I "revived" with a neatfoot bath. Everything is greased with moly in accordance with TBT's assembly guide, and according to this diagram I have all the parts in their correct places:

But looking at TBT kits, there seems to be a piece they provide that sits between the piston and spring, which wasn't already in the rifle, and seems to be unique to that kit.

I feel like the shoe shouldn't be touching the spring, and given that the spring is "correct", perhaps the shoe has become deformed and needs to be flattened out or reshaped? But I'm involving you in my solution here, XY problem and all that.

If you have any ideas, or pointers, or need more information, I'd love to hear from you.

 

[Bazzatron]

Just broke it down again, thought I'd grab the dimensions and some snaps of the cocking arm/shoe.

Disassembly this time required opening the cylinder and winding out the spring, as the cocking arm was very firmly between the coils, which confirms my suspicion, I feel.

Measured with mitutoyo calipers, vernier @0.05mm

Piston inner depth : 95.7

Spring wire diameter: 3.8
Spring ID: 16.25
Spring OD: 23.65
Spring No. Of Coils: 26

 

[Deejayuu]

Ouch! The shoe/foot needs straightening for sure. Common result of excessive spring force or accidental discharge before barrel latched.

 

[Bazzatron]

Ouch! The shoe/foot needs straightening for sure. Common result of excessive spring force or accidental discharge before barrel latched.

So this was what I spent most of my time investigating, and thanks to some really great listing photos for replacement parts on eBay, I was able to be moderately certain this was the case.

Took it apart *again* and took the barrel out to the shop where I found my largest copper hammer.
Inspecting the part, it was clear to me that there were actually a lot of stress cracks at the elbow near the shoe - my hammer lovingly filled these in with copper, so they're very visible now:


so I guess I need to replace this arm next. Hopefully not too much bother. But I've since installed the now flat arm, had to grind the shoe down a little with a diamond burr - the hammering seemed to have widened it too much to actually install. Actually cocks really easily and shoots well. I've been exclusively shooting 177 for a few months, and these 13.8gr .22 pellets feel like absolute monsters.

Anyway, hopefully this thread helps someone in the future, so leaving this all up for posterity.

It has been an interesting project! Learned a lot. Maybe I need to find another totalled rifle to try out hot blueing...

 

[Gummage]

Those stress cracks will open up again methinks, a good replacement arm will be in order, these are lovely rifles.

 

[Bazzatron]

Those stress cracks will open up again methinks, a good replacement arm will be in order, these are lovely rifles.

Yeah, absolutely plan on replacing it. Not quite sure how to punch out the linkages between the segments though - they look quite seriously peened over?
But this fix buys me time

 

[chouchin66]

Yeah, absolutely plan on replacing it. Not quite sure how to punch out the linkages between the segments though - they look quite seriously peened over?
But this fix buys me time

Whilst ordering your new cocking arm, add a steel piston liner to the order. If none in stock specifically for the HW 35, get the liner for an HW 80 - It'll be slightly longer but easy to cut to size a carpenter's " nail set" or steel pin punch & a ball peen hammer will make short work of removing the link rivet. Place arm over a blind hole drilled into a piece of timber, to act as an anvil/ catch basin.

 

[junglie2022]

Ouch! The shoe/foot needs straightening for sure. Common result of excessive spring force or accidental discharge before barrel latched.

Looks to me to have happened if the gun wouldn't cock & has been repeatedly rammed back into the end of the piston cocking slot. I'd check the rear of the piston slot for damage/burrs there to see.

 

[Gummage]

Even repeated 'enthusiastic' cocking can do this over time, mechanical sympathy goes a long way to preventing failures.

 

[Martin Bacon]

I’ve found bent cocking levers on a couple of 35’s in the past. Replaced them with versions that had a Delrin strip in and that sorted it
As previous comments mention - clumsy or over enthusiastic cocking usually the cause!

 

[junglie2022]

Even repeated 'enthusiastic' cocking can do this over time, mechanical sympathy goes a long way to preventing failures.

Yeah no wonder my old back is knackered.....lol.

 

[Bazzatron]

I’ve found bent cocking levers on a couple of 35’s in the past. Replaced them with versions that had a Delrin strip in and that sorted it
As previous comments mention - clumsy or over enthusiastic cocking usually the cause!

I'd love to hear more on this - is that the delrin parts that TBT produces?

 

[Meal Dot]

I try to get a sleeve over the spring of all of my springers, have a couple of old Meteors and they are absolutely smooth and silent cocking. My 35 is quiet too, and FWIW, I have measured the fully compressed spring length available at 105mm. Test alternative springs by compressing on stud bar to check viability.
Not a lot of room in a 35 for springs unfortunately without modifications. Mine is now around 10.5 FPE, full length .22.

 

[junglie2022]

I'd love to hear more on this - is that the delrin parts that TBT produces?

No it's the new mod HW does to the part. Best to remove the too strong spring under it before fitting though. I just modded my 2 old 35's myself with a strip off an old nylon chopping board glued in place with aradite & carefully filed down till it does not cause galling on the inside if the slot too. About half a mm proud of the lever is all you need. The HW 35 k I fettled last year with a bent upwards barrel had a slightly bent cocking lever too witch was dragging on the spring, rattling as you closed the barrel, but it straightened out in the vice ok but while I had it apart again to chop the spring. I added a pop bottle lube sleeve too as a belt & braces cure.