Weihrauch HW55

[nick_mantis]

Hello,

What is the likelyhood of being able to get a replacement piston for an HW55? Mine packed up last week, and removing the cocking lever the piston is sliding separately to the spring.

Sliding it back towards the trigger i can see the slot, and the piston stops just before the 2 sides of the slot meet. It would appear that it has cracked at the fore-end of the slot and the whole front of it has detached and will come out in 2 pieces

[Mach 1.5]

You may have trouble get a 55 Piston but the old HW50 piston will also fit. Failing this I dare say one of the engineers on here could repair or make you a new one? Mach 1.5

[nick_mantis]

Yeah, was kind of expecting that. Already been on the chambers website who carry quite a few spares and a piston they do not have.

The next question would be were all the pistons the same throughout the life of the 55 or were there some changes as with the others. The serial number on mine dates to 1980.

The slight issue is that I have been putting some money aside for a Feinwerkbau or Pardini to be able to retire the Weihrauch for occasional use. But not quite there to go out and buy one yet.

Winter competition season has already started and have about 3 to 4 weeks to get it fixed or possibly withdraw this time and get ready for next year. Also means it needs to be as accurate as it was before last week and not just back together and working.

It's 42 years old so knew at some point there would be an issue that would be difficult to fix easily due to parts, just hoped it would be in the future!

[Mach 1.5]

You could always try protek or place a wanted ad. Chambers will not stock the old HW stuff as it's no longer produce. Mach 1.5

[T 20]

Hello,

What is the likelyhood of being able to get a replacement piston for an HW55? Mine packed up last week, and removing the cocking lever the piston is sliding separately to the spring.

Sliding it back towards the trigger i can see the slot, and the piston stops just before the 2 sides of the slot meet. It would appear that it has cracked at the fore-end of the slot and the whole front of it has detached and will come out in 2 pieces

As your latch rod sounds to be OK, a piston repair by having a new piston body machined up would be the easiest long term fix option.
The piston bodies are just made from mild steel so anyone with a small lathe should be able to make one.
The only big decision to make is do you go with the original leather piston seal or do you machine the new body to accept a synthetic seal ?



All the best Mick

[rapidshot]

Sent you a PM

[evert]

Could you take some pictures of the piston?

[deejayuu]

Got two early 50 pistons on way from Netherlands. Not cheap but may be able to assist. I only really need one but saw this and bagged both.

[nick_mantis]

Misplaced my punch set but finally got everything apart this week.

Hmmm, maybe not quite standard. Anyone recognise it?

[evert]

Misplaced my punch set but finally got everything apart this week.

Hmmm, maybe not quite standard. Anyone recognise it?

Not standard at all, but very interesting, and perhaps example of tuning work?

I've been thinking about assembling pistons like this, with front plugs threaded into the piston body.
But this seems like a good example of how threads will be stress risers in the design of a piston.
At the same time, milling the cocking slot that far into the threaded portion of the piston is asking for trouble.

Has the gun had any cylinder damage from the piston failure?

[nick_mantis]

Need to have another look to make sure but didnt notice any scratch's when looking down the bore.

Looking at it and comparing it to any pictures you can find of the stock piston the front looks very similar. So it could be a stock piston that has been cut down and and threaded, which would account for the slot being so far into the thread as it was already in there to start with.

The threads don't look to have been damaged either so it might be possible to replace the body..... if anything fits on it.

It is in the full match stock so tuning during its life is well within the realms of possibility.

[T 20]

Misplaced my punch set but finally got everything apart this week.

Hmmm, maybe not quite standard. Anyone recognise it?

I'm not the world expert on these things but that piston doesn't look like a Weihrauch product to me, every Weihrauch piston I've ever seen has been brazed and pinned together.

It could be a custom piston or it could be a piston from a different manufacturer.

HW50 piston :-

image.jpg





All the best Mick

[deejayuu]

Here's a couple of 55 pistons
One earlier than the other https://photos.app.goo.gl/zwV6odNxi1gN1xQQ8

[crowbar]

Comparing the pic's it looks like the lower one of the two, so I think it is original piston with a O ring piston mod and a extra slot? to lighten the piston but I can't see for the latch rod.

[deejayuu]

Comparing the pic's it looks like the lower one of the two, so I think it is original piston with a O ring piston mod and a extra slot? to lighten the piston but I can't see for the latch rod.

The 50 has steel head and one slot. The 55 has the alloy head and two slots to reduce weight. Not convinced the stock 55 is threaded head tho'. Thought it was interference with cross pin. May have to investigate.