I'm Sat Waiting On Postman Pat

[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

[BTDT]

The HW50 piston weighs 186 gm, the HW55 163 gm. The HW55 piston head is aluminium, and extends back into the piston, giving available length for the compressed mainspring of 95.6mm in the 55, against 108mm in the 50.

I suspect that if Venom used the HW50 piston in their 55, it was as much for the extra spring room as the mass.

[evert]

The HW50 piston weighs 186 gm, the HW55 163 gm. The HW55 piston head is aluminium, and extends back into the piston, giving available length for the compressed mainspring of 95.6mm in the 55, against 108mm in the 50.

I suspect that if Venom used the HW50 piston in their 55, it was as much for the extra spring room as the mass.

I really need to open up a few of the ones we have in the family, we have to different 55's and several different 50's, would be interesting to see if there are even more variations between them.

[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]

The HW50 piston weighs 186 gm, the HW55 163 gm. The HW55 piston head is aluminium, and extends back into the piston, giving available length for the compressed mainspring of 95.6mm in the 55, against 108mm in the 50.

I suspect that if Venom used the HW50 piston in their 55, it was as much for the extra spring room as the mass.

Cheers for that, Jim.

I'm now looking at making a custom piston using a threaded 77 latch rod, by doing this I can have the minimum wall thickness between the front of the spring and the rear of the seal, giving the maximum Spring room.

I've found some Titan springs in my pile with a 19mm OD made from 3mm wire which I think will fit the bill, by using one of these I can increase the wall thickness of the piston to bring the weight back up to make up for the lighter front end.
If I can manage to keep a decent wall thickness at the rear of the piston then I can fit a bearing to it to make up for me using mild steel for the piston body.




All the best Mick

[T 20]

I really need to open up a few of the ones we have in the family, we have to different 55's and several different 50's, would be interesting to see if there are even more variations between them.

Hi Evert.

I've seen a few variations in 35 Pistons so I expect the 50 to have had the same variations over the years.

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

Hi John.

The piston I've been playing with is all steel and originally had a synthetic HW seal and a stroke of 65mm, whether later 25mm 50s changed from a 65mm stroke to a 69mm stroke in line with the HW35 I couldn't say.

I don't really need another gun but it would be nice to see what could be done with this little thing.

I really should dig out the original barrel and date the action from the serial number to get an idea of it's age and history




All the best Mick

[evert]

......
The piston I've been playing with is all steel and originally had a synthetic HW seal and a stroke of 65mm, whether later 25mm 50s changed from a 65mm stroke to a 69mm stroke in line with the HW35 I couldn't say.

......


All the best Mick

That explains a lot, the piston I'm working on is an older leather sealed one.

[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.

[TonyL]

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

The HW50 piston weighs 186 gm, the HW55 163 gm. The HW55 piston head is aluminium, and extends back into the piston, giving available length for the compressed mainspring of 95.6mm in the 55, against 108mm in the 50.

I suspect that if Venom used the HW50 piston in their 55, it was as much for the extra spring room as the mass.

Brilliant information.

[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

[evert]

.....
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

OR you could drill out the locking pin, unsolder the piston body from the piston front, and shorten the rod of the piston your are working on?
Maybe make up a new piston front and use the piston body and rod, shortened to give you the maximum stroke available with these components?

[T 20]

OR you could drill out the locking pin, unsolder the piston body from the piston front, and shorten the rod of the piston your are working on?
Maybe make up a new piston front and use the piston body and rod, shortened to give you the maximum stroke available with these components?

That's a lot more work than you'd imagine, Evert --- it would be quicker to build a new piston from scratch.

I still think starting with a 99 piston would be the quickest option, but until I have one in my hands I'm only guessing.





All the best Mick