HW35 mods?

[landymick]

If you can avoid it - like it

You won’t actually see any thing ,maybe a dirty edge around end plug . I used a syringe on the end of some flexi pipe to administer the loctite all around the edge .

[TonyL]

Yep, I seem to remember reading how a few people use syringes with long straws attached to administer the sealant. I was going to but didn't have a suitable straw to hand. So I just made a bung up for the transfer port, aimed the JB down at the bottom of the cylinder and swirled it about (it's quite runny), then compressed it into the end of the cylinder with the old and to-be-discarded piston seal.

[GreenwayJ]

Bowkett used to do many conversons on the HW35 in the 1980s. They went against current trends but they were in high demand and paid his mortgage so he must have done something right. He told me that he used a 4 mm port, lined the piston with a thick steel sleeve, fitted a steel top hat and used one of his universal springs made for him by a chap called Mike wade. These were 24 coils and of much smaller outside diameter and wire than standard. The piston was also fitted with his piston head. The result after being "balanced" was a very soft shooting full power rifle, the .22" versions had to be de-tuned, and amzingly quiet.
Just goes to prove there are more ways than one of skinning a cat

[randl]

Bowkett used to do many conversons on the HW35 in the 1980s. They went against current trends but they were in high demand and paid his mortgage so he must have done something right. He told me that he used a 4 mm port, lined the piston with a thick steel sleeve, fitted a steel top hat and used one of his universal springs made for him by a chap called Mike wade. These were 24 coils and of much smaller outside diameter and wire than standard. The piston was also fitted with his piston head. The result after being "balanced" was a very soft shooting full power rifle, the .22" versions had to be de-tuned, and amzingly quiet.
Just goes to prove there are more ways than one of skinning a cat

Thanks for that , very interesting.

[randl]

Thinking ahead a bit because I’m no there yet !
Is a piston sleeve a good idea? And if so what’s the best material?
I’ve heard of beer cans , milk bottles and ptfe sheet or does someone produce a ready made one .
Thanks

[TonyL]

The "luxury" premium sleeve would be one made from shim steel.

I think some off the shelf items are available - maybe from Chambers Airgun Spares or John Knibbs?

However, many people have enjoyed success with home made items and they're easy to make. Materials can be PTFE sheet, drinks cans, plastic bottles etc., as you mention. Many drinks cans these days are aluminium. If you preferred steel, I think Jon Budd said that WD40 cans were steel? Generally considered harder wearing than aluminium. And many of us have been spotted trawling supermarket shelves armed with magnets in the past!

[gtfreight]

The "luxury" premium sleeve would be one made from shim steel.

I think some off the shelf items are available - maybe from Chambers Airgun Spares or John Knibbs?

However, many people have enjoyed success with home made items and they're easy to make. Materials can be PTFE sheet, drinks cans, plastic bottles etc., as you mention. Many drinks cans these days are aluminium. If you preferred steel, I think Jon Budd said that WD40 cans were steel? Generally considered harder wearing than aluminium. And many of us have been spotted trawling supermarket shelves armed with magnets in the past!

I once spent an hour in Asda with a Vernier guage looking at everything from hollow mop handles to Steradent tubes to find a ready made sleeve (without success).

[TonyL]

I once spent an hour in Asda with a Vernier guage looking at everything from hollow mop handles to Steradent tubes to find a ready made sleeve (without success).

Spooky!. I've done exactly the same at home with various vitamin tubes etc. and at the supermarkets (but without the gauge at the supermarkets). I think we're infected, er, I mean, infectious.....or somefink!

[randl]

Ok Hw35 gurus .
After a lot of cleaning and faffing around I’ve got to the putting it back together stage.
I did the leaky breach fix just in case.After a proper measure this time turns out the transfer port is 2.8mm so ordered a new type piston with seal from Chambers .
I had to trim 10mm off of the rear tbt spring guide to get it to fit and the original spring at 27 coils was too long . Luckily I had one in box from years ago at 25 coils and fits perfectly and the action feels smooth and cocks outside of the stock .
This is where the problem lies . When put back in the stock it won’t cock as the barrel latch is making contact with the stock preventing the piston travelling back to engage.
So where do I go from here ?!
Cheers R

[tinbum]

Ok Hw35 gurus .
After a lot of cleaning and faffing around I’ve got to the putting it back together stage.
I did the leaky breach fix just in case.After a proper measure this time turns out the transfer port is 2.8mm so ordered a new type piston with seal from Chambers .
I had to trim 10mm off of the rear tbt spring guide to get it to fit and the original spring at 27 coils was too long . Luckily I had one in box from years ago at 25 coils and fits perfectly and the action feels smooth and cocks outside of the stock .
This is where the problem lies . When put back in the stock it won’t cock as the barrel latch is making contact with the stock preventing the piston travelling back to engage.
So where do I go from here ?!
Cheers R

You say you've ordered a new style piston and seal, is this the one you are fitting?
If not, stop until you get in, if yes the extra stroke means the slot may need lengthening.

More detail and pics would be good about now

[randl]

Hopefully I can clarify.The gun dates from 1981-1982 and had leather sealed piston and 2.8mm transfer port.
Yes the new piston with synthetic seal is fitted . After watching your very helpful videos showing how to measure guide length and determine spring length I made some adjustments and I’m happy with the way it feels and cocks outside of the stock.
When fitted in the stock during cocking the barrel latch thumb lever is coming up against the wood in the stock cutout before the piston rod has travelled back far enough to engage with the trigger.
The original roller type cocking lever is still fitted, do I need to change that for the newer delrin version , will that push the piston back further before the catch makes contact with the stock .

[tinbum]

The original roller type cocking lever is still fitted, do I need to change that for the newer delrin version , will that push the piston back further before the catch makes contact with the stock .

Someone with more experience will give a definitive answer soon I'm sure, but if the starting point is the same I would think it just needs more travel to accommodate the extra stroke rather than a different cocking arm.
I would expect the result will be a small modification of the stock, but wait for Mick, Jon or someone cleverererer to confirm before sharpening the axe.

[randl]

Yes I did think that might need to happen!
I won’t do this until confirmed though .
Cheers

[TonyL]

Hopefully I can clarify.The gun dates from 1981-1982 and had leather sealed piston and 2.8mm transfer port.
Yes the new piston with synthetic seal is fitted . After watching your very helpful videos showing how to measure guide length and determine spring length I made some adjustments and I’m happy with the way it feels and cocks outside of the stock.
When fitted in the stock during cocking the barrel latch thumb lever is coming up against the wood in the stock cutout before the piston rod has travelled back far enough to engage with the trigger.
The original roller type cocking lever is still fitted, do I need to change that for the newer delrin version , will that push the piston back further before the catch makes contact with the stock .

Couple of things.......

Firstly, are the latch, groove and spring lubed, moving freely and not sticking?

Secondly, as far as I'm aware, the piston switch shouldn't necessitate a change of cocking lever under normal circumstances. Is it bent, perhaps? But then if it cocks fine when the stock isn't fitted.......???

[TonyL]

Someone with more experience will give a definitive answer soon I'm sure, but if the starting point is the same I would think it just needs more travel to accommodate the extra stroke rather than a different cocking arm.
I would expect the result will be a small modification of the stock, but wait for Mick, Jon or someone cleverererer to confirm before sharpening the axe.

When fitting the new piston you just need to make sure there's enough clearance between the lever shoe and the slot. Mine was fine. I think Mick has said in the past that he's had to relieve the slot in the piston in the odd one to gain sufficient clearance?