HW77 springy underlever

[AC all day]

Sounds like you are saying the end of the compression tube sticks out from the walls of the compression tube. That would make the breech area hit the end of the barrel and try to pop the under lever back out. Not sure what holds the plug in the head end of the comp. tube, but maybe it has been "modified" for a tighter lock up. Machining the end of the tube flush won't help because it's the recess for the breech seal that's hitting the barrel.

That is what I am trying to say.....even with the breech seal removed it still does it.....not so bad but, still pops back open.

[Bruno27]

May be try a very small piece of bluetack on the face of barrel to see if it get squashed (as metal to metal)

[bozzer]

I've been following this thread with interest ...

So there is no lead build up around the end of barrel at the breech? None on the inside/front of the action tube ( just under the area that is cut out ) and non on the actually end of the barrel?

So the end of the comp tube ( something ) hits the barrel or the front of the action tube ... even with no breech seal fitted! Do we know if it's the front of the comp tube head hitting the action ... or the inside of the comp tube head recess ( where seal should be ) hitting the end of the barrel?

The cocking link slots into the rectangular hole of the underside of the comp tube. That little lip stops it from falling out. So the back of that square part on the cocking link pulls on the comp tube to return the comp tube to the firing position as the cocking lever is returned to the firing position.

Are there any burrs on either the cocking link bit that sits in the comp tube ... or any burrs on the comp tube rectangular slot? Those links are hardened. Maybe there's some abnormality at that back end of that square bit that sits in the comp tube that needs trimming with a bench grinder. Just a tiny excess there will cause a tight lock up.

Have a look at the very end of the barrel breech. Sometimes on the very face of the barrel breech there are proud lines. I've sometimes smoothed those off to get the comp tube and breech seal giving a better seal to the barrel. I can't see them being that proud that it will cause this ... without a seal in ... but have a look.

How much ... accurately ... does the head of the comp tube stick out from the outer tube of the comp tube?

I also don't know/can't remember how that is fixed. I can't believe it's screwed in. So I presume its pinned. Either way it seems strange to think that it has been pushed forward.

I know you say you've checked but it still seems like a cocking link issue. Ideally try another cocking link. Check for burrs first on your cocking link and comp tube where the cocking link attaches.

[AC all day]

Ok so more things tried.....
I part inserted a pellet into the breech and closed the underlever. The pellet was a fingernail proud( no seal fitted). The lip on the compression chamber is 2/10ths of a mm......and it's still the original cocking arm as the rivit is unmolested.....I add this IS an early gun at 1291***.....surely it's not me being picky.....
With the lever pin out and a transfer punch in place.....no probs, but that's fractionally under size and surely not right....
Cheers for all the advice,

[T 20]

Ok so more things tried.....
I part inserted a pellet into the breech and closed the underlever. The pellet was a fingernail proud( no seal fitted). The lip on the compression chamber is 2/10ths of a mm......and it's still the original cocking arm as the rivit is unmolested.....I add this IS an early gun at 1291***.....surely it's not me being picky.....
With the lever pin out and a transfer punch in place.....no probs, but that's fractionally under size and surely not right....
Cheers for all the advice,

I'd just cut the lip off and try again, ideally you just want the cylinder contacting on the breech seal.

I normally radius the front and rear of the compression tube so there should be no problem in just machining the lip off.




Bozzer :- the end plug on the Weihrauch cylinder is said to be threaded in and sealed with loctite --- back in the day, tuners used to remove the plug in order to radius the inside of the transfer port.

[crowbar]

The end plug on my 77 is flush with the comp tube wall .

I would take the cocking link off and with everything spotless clean measure and check comp tube fit to barrel,
then offer cocking link to it to see line up of cocking link to pivot hole and if out of line bend the tang bit to suit .

I think it is this that is bent as the straight bit is far stronger , and that is the weakest bit .

I have repaired 77's with this problem before having to weld some at the bend as they had cracked !

[crowbar]

The only other thing is if the end plug is sticking out a mil or two is give it some heat and screw it out and clean it up
and see if it will screw in another turn , and check it but I have never done this myself so it's all theory .

[T 20]

The only other thing is if the end plug is sticking out a mil or two is give it some heat and screw it out and clean it up
and see if it will screw in another turn , and check it but I have never done this myself so it's all theory .

Nope, if you read through the thread again, the plug isn't sticking out, the plug is recessed into the cylinder leaving the lip of the cylinder proud of the plug.

The transfer port is not contacting the barrel as the lip is contacting the end of the action holding the transfer port off the barrel.

Which tells us the cylinder is the correct length from the cocking lever window to front face of plug, but the lip makes the cylinder too long for the action.

The simple solution is to machine the lip off the front of the cylinder --- note the cylinders are fairly hard so the lip will probable need grinding off with a dremmel before finishing.





All the best Mick

[TonyL]

then offer cocking link to it to see line up of cocking link to pivot hole and if out of line bend the tang bit to suit .

I think it is this that is bent as the straight bit is far stronger , and that is the weakest bit .

I have repaired 77's with this problem before having to weld some at the bend as they had cracked !

I'm also of the thinking that this could be the problem.

[bozzer]

Sounds like you are saying the end of the compression tube sticks out from the walls of the compression tube. That would make the breech area hit the end of the barrel and try to pop the under lever back out. Not sure what holds the plug in the head end of the comp. tube, but maybe it has been "modified" for a tighter lock up. Machining the end of the tube flush won't help because it's the recess for the breech seal that's hitting the barrel.

That is what I am trying to say.....even with the breech seal removed it still does it.....not so bad but, still pops back open.

Nope, if you read through the thread again, the plug isn't sticking out, the plug is recessed into the cylinder leaving the lip of the cylinder proud of the plug.

The transfer port is not contacting the barrel as the lip is contacting the end of the action holding the transfer port off the barrel.

Which tells us the cylinder is the correct length from the cocking lever window to front face of plug, but the lip makes the cylinder too long for the action.

The simple solution is to machine the lip off the front of the cylinder --- note the cylinders are fairly hard so the lip will probable need grinding off with a dremmel before finishing.

All the best Mick

Mick

I'm reading it the other way around. I'm reading that the nose sits proud of the comp tube walls.

Bozzer :- the end plug on the Weihrauch cylinder is said to be threaded in and sealed with loctite --- back in the day, tuners used to remove the plug in order to radius the inside of the transfer port.

Cheers for that Mick


So I'm still understanding this as the nose sits slightly proud ( in front of ). I'm presuming that's the 2/10 of a mm. So that's 0.2mm. That's not a lot when you think the TP seal is normally a couple of mm and this rifle is causing a problem without a seal.

For me it has to be a cocking link issue. It's either got burrs on the bit that fits in the comp tube cut out, or, as stated above, there is a problem where it attaches by the underlever.

I have seen excessive lines on the very end ( flat face ) of the barrel ... but only a few thou that needs smoothing off carefully.

Ideally I'd try another underlever and cocking link. That's fine if like me you have more than one 77 lying around.

[bozzer]

Grrr I still can't edit posts.

That's reading and not treading.

[bozzer]

So I'm still understanding this as the nose sits slightly proud ( in front of ). I'm presuming that's the 2/10 of a mm. So that's 0.2mm. That's not a lot when you think the TP seal is normally a couple of mm and this rifle is causing a problem without a seal.

Unless it's the front of the nose hitting the front of the action and not the inside of the recess hitting the end of the barrel ... but 0.2mm is still small.

Anyone know why I can't edit posts since I changed to a newer laptop?. It's driving me bonkers ( er ... more bonkers )

[T 20]

I'm just going on this, Bozzer :-

The lip on the compression chamber is 2/10ths of a mm,

I'm taking it that to create a lip the plug would be recessed into the tube, and even though it's only an 8 thou" lip it would be enough to cause problems.

If the OP had said an 8 thou" step I'd be advising to screw the plug in another turn as Crowbar posted.



All the best Mick

[bozzer]

Totally agree re lip and step ... but I still think he means the nose is 0.2mm forward of the outer tube of the comp tube. Hopefully he'll confirm.

[bozzer]

... and thank you for editing treading to reading.

I must sort out this editing problem with this laptop.

0.2mm may be a prob ... but he's saying it's still a prob with no seal in there. The seal must be a couple of mm.