I'm Sat Waiting On Postman Pat

[HW777]

Threaded interchangeable piston heads and shallow piston seals would assist with piston stroke length in Mk1 Hw50's

Rather time consuming though but something to consider if you have the time and skill to do it

[T 20]

Threaded interchangeable piston heads and shallow piston seals would assist with piston stroke length in Mk1 Hw50's

Rather time consuming though but something to consider if you have the time and skill to do it

Hi John

If my calculation of the HW99 piston length being 146mm overall, then by machining the Weihrauch piston seal arbor off to expose the piston rod, I could thread the rod to use interchangeable piston heads.
By doing this I could easily alter the stroke between 71mm up to 76mm.

The other alternative I've been looking at is using a TX200 latch rod in a homemade piston body, I could then simply increse the stroke by screwing the rod further into the body --- I'd need to alter the Rekord top sear to use the TX rod but that's a simple enough operation.

Something else I need to have a Squint at is the possibility of using the piston I've already altered but extending the stroke by moving the Rekord pin holes backwards in the back block.
This would increase the stroke and also give a setback trigger, but I have a feeling there's not enough room in the block to do it.




All the best Mick

[TonyL]

Something else I need to have a squint at is the possibility of using the piston I've already altered but extending the stroke by moving the Rekord pin holes backwards in the back block.
This would increase the stroke and also give a setback trigger, but I have a feeling there's not enough room in the block to do it.

All the best Mick

Wow! Now that is extreme thinking out of the box. Guessing, like you say, that there may not be enough room to allow this, but you never know.........

[T 20]

Something else I need to have a Squint at is the possibility of using the piston I've already altered but extending the stroke by moving the Rekord pin holes backwards in the back block.
This would increase the stroke and also give a setback trigger, but I have a feeling there's not enough room in the block to do it.

Wow! Now that is extreme thinking out of the box. Guessing, like you say, that there may not be enough room to allow this, but you never know.........

Yes, Tone --- after measuring it up there wouldn't be enough gain to make it worthwhile.

A little trick I do when long stroking HW35s to check if the cocking linkage will still work at a longer stroke is to remove the mainspring and wind out the back block by the amount I'm adding to the stroke, and check that it still cocks.
That's to say if I'm stroking a synthetic sealed HW35 from it's standard stroke of 69mm to 71mm I unscrew the back block by 2mm and check that the gun still cocks.

Having just remembered this trick I'll have a little play with a HW50 this afternoon and see what it can be stroked to.




All the best Mick

[Mach 1.5]

Hi Mick. Back in the early 80s Venom would use the piston from the HW50 and use it in their HW55 conversion. As the 55 piston was to lite. Hope that helps in someway? Regards Mach 1.5

[T 20]

Hi Mick. Back in the early 80s Venom would use the piston from the HW50 and use it in their HW55 conversion. As the 55 piston was to lite. Hope that helps in someway? Regards Mach 1.5

Hi Paul.

It's very difficult to say what model the piston I've been playing with in this 50 came out of as the action was bought off the Bay.

What I can say for sure is that it had a 65mm stroke and with the loss of a little metal to fit the TX seal it now weighs in at 186 grams, Presently with 69.5 mm stroke it has an overall length of 147.5 mm.
I'm now working on the assumption that the HW99 piston with its 71 mm stroke has an overall length of 146 mm, so by replacing the 10 mm wide HW seal with a 5 mm wide TX seal I could stroke it by 5 mm to 76 mm.
From measuring the cylinder this afternoon I've found that the compression chamber is 76.5 mm long and by winding the back block out the cocking linkage will still work with a 75 mm stroke so that's what I'll be aiming for now.

By using a HW99 piston rod and making my own piston body I could add weight to the body to get nearer to a 200 gram piston weight.






All the best Mick

[Mach 1.5]

Thanks for interest info Mick. Hoping to get mine 're-barrelled in .22 also. Mach 1.5

[HW777]

Hi Paul.

It's very difficult to say what model the piston I've been playing with in this 50 came out of as the action was bought off the Bay. :rolleyes

All the best Mick

Hi Mick

If the piston in question has a alloy block visible where the piston rod connects with the piston head, it's a fair bet it came from a 55

Very keen to see how you progress with this Hw50

All the best

John

[T 20]

I'm now working on the assumption that the HW99 piston with its 71 mm stroke has an overall length of 146 mm, so by replacing the 10 mm wide HW seal with a 5 mm wide TX seal I could stroke it by 5 mm to 76 mm.

Well I was way off with that assumption.

It appears that the HW99 piston is 156mm long and not 146mm as I'd expected, after further reading it turns out that ONLY the external dimensions of the HW99 action are the same as an Old School HW50 action.

When Weihrauch changed from the Old School 50 to the HW99 they increased the cylinder bore from 25mm to 26mm, they increased the piston stroke from 65mm to 71mm, but more importantly to my search for a suitable piston Weihrauch shortened the transfer port from 26mm to 16mm --- a full 10mm.
This explains why the HW99 piston is a full 10mm longer than I expected as the internal length of the cylinder is 10mm longer than the Old HW50.

I could possibly still use a HW99 piston by machining off the Weihrauch seal arbor then machining the front of the piston to accept a TX seal giving me a 71mm stroke.

But I may just park this one up again while I wait and see what appears in the sales section this year.






All the best Mick

[TonyL]

A little trick I do when long stroking HW35s to check if the cocking linkage will still work at a longer stroke is to remove the mainspring and wind out the back block by the amount I'm adding to the stroke, and check that it still cocks.
That's to say if I'm stroking a synthetic sealed HW35 from it's standard stroke of 69mm to 71mm I unscrew the back block by 2mm and check that the gun still cocks.

All the best Mick

Nice one, Mick.