HW35 mods?

[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]

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?

[randl]

Thanks Tony all lubed and not sticking or bent all in great shape. Feels great cocking out of stock, just wo t in stock.
I think there must be a clearance issue somewhere ?!
Your suggestion may be right but I’m not quite sure what you mean.
Thanks

[Shed tuner]

basics.. if it cocks fine without the stock, but not with the stock, then (wait for it) - it's the stock or fitment thereof stopping it cocking.

Have you tried cocking it without the stock fitted ? It takes a bit of strength and technique on an HW35. I lay the action upside down on a towel on a bench, with an end stop, and you can then use both hands for good control.

If the stock is indeed causing the problem, check easy stuff first.. is the latch definitely actually hitting the woodwork at the cutout ? As Tony says, is it returning under it's spring to it's fully back position ? If it is, then sure, just scoop out a little wood.
Also check stock screws - if they are going in too deep they could be fouling the cocking linkage. Same with the rear trigger guard screws.

In terms of the extra stroke, with stock removed, just take a look and see if there is clearance between the rear of the piston cocking slot and the cocking shoe - at least 1mm needed. Then, when cocking the gun (out of stock), see if you have enough rear slot length to cock it. You may need to lengthen the slot a few mm (dremel is fine) to make up for the extra stroke.

I will say the extra stroke piston makes such a huge difference, so it's well worth it.

HTH - JB

[TonyL]

Perfect sum-up, JB, and the answer has to be amongst the above..

[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.......???