Weihrauch HW55

[TonyL]

To be honest the piston looks like the modifications to it turned it into a right old knacker, I'm just happy for Nick that the cylinder came out of this unscathed.

As I said earlier in the thread, it would be a simple job to machine up a new piston using the salvaged latch rod from the old one.

All the best Mick

Jumping in very late on this. Sorry. But 100% what Mick says.

There will be people out there able to undertake this work, but many of these would only do so for their own projects. Thinking NickG might be able to assist?

[T 20]

Jumping in very late on this. Sorry. But 100% what Mick says.

There will be people out there able to undertake this work, but many of these would only do so for their own projects. Thinking NickG might be able to assist?

My big problem with making custom parts for other folks is that I like to take my time and I couldn't possibly charge an hourly rate accordingly, Tone.
The Pistons I've shown that I've made have all been for my own guns, so I never take the cost into consideration with them.

I'd rather leave the custom parts making to other folks rather than get too involved in things so I would also recommend NickG for this.




All the best Mick

[HW777]

My big problem with making custom parts for other folks is that I like to take my time and I couldn't possibly charge an hourly rate accordingly, Tone.
The Pistons I've shown that I've made have all been for my own guns, so I never take the cost into consideration with them.

I'd rather leave the custom parts making to other folks rather than get too involved in things so I would also recommend NickG for this.




All the best Mick

I've been asked to tune other people's rifles Mick but back off when they only want power above performance

DJ has offered Nick a piston and given they are a obsolete part and hard to find, that would be an ideal opportunity for him to replace his broken piston

As to converting Hw 25mm pistons from leather to synthetic, the early model smk B20 seal looks like a good option, plenty of extra sweep volume but I wonder how the compare the a tx seal ?

Atb

John

[T 20]

As to converting Hw 25mm pistons from leather to synthetic, the early model smk B20 seal looks like a good option, plenty of extra sweep volume but I wonder how the compare the a tx seal ?

Atb

John

Hi John.

If the B20 has become the X20 then it's a copy of the Weihrauch HW85/95 and has a 26mm cylinder :-

image.jpg

The TX seal and a few Diana and SMK seals are 25mm with the same dovetail fixing as the X20, I tend to use the TX seal when long stroking the 25mm cylinder Weihrauchs.
The Weihrauch seal is 10mm long, the TX seal is 5mm long, so by simply machining the Weihrauch seal arbor down into a TX dovetail arbor you get a piston with 5mm of extra stroke.
The piston cocking lever slot also needs extending a tad for this modification but basically it's a very simple modification that you can either use to increase power output or use at the original power output with less Spring length.

The X20 seal shown could be useful for longstroking a HW95 (God knows why you'd want to) or longstroking a HW99 as their cocking geometry will easily cock a 76mm stroke piston.





All the best Mick

[nick_mantis]

Just found this over on airgunation. HW55T being stripped for a new leather seal. Same 2 piece construction, aluminium/steel, and it's threaded! It is the exact same piston so either someone was selling aftermarket pistons or Weihrauch were threading the cylinder onto the head. Will be interesting to see what DJ finds investigating his. Even the machining is the same. Welds not so sure, might just show up on mine because they have gaps and dirt in them.

If anyone is junking an old piston with a damaged head but good tube I have a kidney here with your name on it....well not literally......don't think tatoo's go that deep....

[evert]

Just found this over on airgunation. HW55T being stripped for a new leather seal. Same 2 piece construction, aluminium/steel, and it's threaded! It is the exact same piston so either someone was selling aftermarket pistons or Weihrauch were threading the cylinder onto the head. Will be interesting to see what DJ finds investigating his. Even the machining is the same. Welds not so sure, might just show up on mine because they have gaps and dirt in them.

If anyone is junking an old piston with a damaged head but good tube I have a kidney here with your name on it....well not literally......don't think tatoo's go that deep....

Does not look like this one has the same welds as yours did.
Remember that the threads on your aluminium piston head probably are damaged when the body slipped off- replacing the body while keeping the head may lead to just another failure.

But the piston in the last picture had the same serious flaw as yours did- the cocking groove covers very much of the threaded area.
If a piston is made up with threaded body all the way up to the seal, I suspect it may be a lot stronger.

[nick_mantis]

I see what you are saying, and as you can see on mine there is a washer butted up against the aluminium head that would stop the cocking lever from getting that far up the slot so there doesn't seem to be any reason for it other than to save weight. To be that perfectly line up as well with a cross pin has it been assembled, pinned, and then the slot milled through everything?

Whatever they did looks like I need a like for like to keep the action as fast as it is. Also looking at DJ's 2 pistons the older steel one is shorter, ie. if the same spring was used with both pistons the aluminium head doesn't let the spring decompress as much (ignoring the 2 thicknesses of seal). If I dropped in a shorter piston could that induce bounce at the end of the firing stroke, and then would be looking at trying to get a spring to match a new piston to keep everything within competition levels.

Only needed a few months out of it too as was going to retire the Weihrauch for occasional use and upgrade to a PCP for competition.

Does not look like this one has the same welds as yours did.
Remember that the threads on your aluminium piston head probably are damaged when the body slipped off- replacing the body while keeping the head may lead to just another failure.

But the piston in the last picture had the same serious flaw as yours did- the cocking groove covers very much of the threaded area.
If a piston is made up with threaded body all the way up to the seal, I suspect it may be a lot stronger.

[TonyL]

My big problem with making custom parts for other folks is that I like to take my time and I couldn't possibly charge an hourly rate accordingly, Tone.
The Pistons I've shown that I've made have all been for my own guns, so I never take the cost into consideration with them.

I'd rather leave the custom parts making to other folks rather than get too involved in things so I would also recommend NickG for this.

All the best Mick

Absolutely 100% with you, Mick.