Webley Mk3 (serial 9350) - Piston Washer Advice

[chieffool]

My Dad's bought from new. I know from the Webley site that these were made 1947-71, so it must need a new washer by now! Surely?

Does anyone have a better suggestion for a replacement washer than:
http://www.airgunspares.com/store/ca...EY/Webley-Mk3/

They show a leather washer for £15, but does anyone make anything more modern and durable than just 'leather' for this gun?
I realise its not a modern air gun in performance terms, but it would be great to make it as good as it can be.

cheers
R

[oliver13]

Leather washers are surprisingly good at the job, don't be surprised if it's still OK even after a long career. Back in my lathe days I made an 'O' ring head for a mates HW35 & there wasn't a great deal of difference from the leather original, then he put an Ox spring in it, the less said about that the better.

One thing, £15 is a bit eye watering for a replacement washer, it actually gets a whole new piston head, in practise they are easy to make for a few pence. Item no. 191219758842 on the 'Bay for £3.50 as example gets more than enough raw material.

[flatrajectory]

The Webley mk3 being a tap loader does not suit a modern synthetic seal at all. If fitted it would be horrible to shoot...slammy and harsh. Don't do it.
The standard leather seal,if correctly sized and lubricated will give many years of sterling service. If the gun needs one, get the unit from John Knibbs. I speak from over 35 years experience in airgun repair and ownership.
Pete.

[chieffool]

Many thanks. Sound advice. A friend borrowed my new chrono, but will try it out to see what she's pumping out later this evening. Never occurred to me that after all this time it might still be 'good'.

[chieffool]

The Webley mk3 being a tap loader does not suit a modern synthetic seal at all. If fitted it would be horrible to shoot...slammy and harsh. Don't do it.
The standard leather seal,if correctly sized and lubricated will give many years of sterling service. If the gun needs one, get the unit from John Knibbs. I speak from over 35 years experience in airgun repair and ownership.
Pete.

Can i ask which lubricant do you suggest for the washer?

[chieffool]

Many thanks. Sound advice. A friend borrowed my new chrono, but will try it out to see what she's pumping out later this evening. Never occurred to me that after all this time it might still be 'good'.

just put it thru the Chrono (Combro CB-625). Definitely needs a new washer......

[AC99]

One of my mk3's which I have owned since 1959 was fitted with a new leather washer by me in the same year (when I was quite young ) and still shoots as well now with that same washer as it did 55 years ago although the rifle did not have a great deal of use for 25 years or so when it was stored. It is important that the washer is not allowed to dry out so you need to keep it oiled especially when stored, unused for very long periods. I would NOT be tempted to go along the synthetic washer route.
Aubrey

[flatrajectory]

Can i ask which lubricant do you suggest for the washer?

The very best treatment for the leather washer is Neetsfoot Oil, available from most good horse/ riding supply outlets. But you can get away with modern oils if you have to. The main thing is that the new washer as supplied will be oversize and too tight to enter the cylinder. You will need to CAREFULLY reduce the diameter slightly using a bench grinder or belt sander. A hand file will also work but take longer. Only when you have got the seal ( must be fitted to the piston) to a nice sliding fit ( with some friction) should you then remove the seal and soak it overnight in neetsfoot oil, then re fit.
The problem with leather piston seals is that if the gun lies unused for a long while the leather dries out and the pressure of the mainspring and piston causes it to stick to the cylinder wall. If this happens, the next time the rifle is cocked the outer lips of the seal remain bonded to the cylinder wall. The gun will fire but with insufficent power to propel the pellet.
Pete.

[martintheveg]

Some very good info on this thread for a new mark 111 owner, and some very knowlegable gun owners too, thanks for your input fellas.

[chieffool]

many thanks all. Leather washer arrived promptly. will strip out and follow the advice (ref fitting, soaking, etc). Need to make up a bench clamp with some wood and a big G clamp later this week to strip down. Confident all will be fine (though fitting a tuning kit from Tinbum on my TX200HC is a lot easier).

What a fantastic forum this is!!

[chieffool]

One final bit of info I gleaned from a previous thread (29-8-2014) quoting from 'nige346' which i've included in case someone is checking through this for similar info in the future:

"MK3 should have a leather seal assembly, easily available fron j knibbs or chambers, soak the washer in leather seal treatment before fitting, once fitted leave it for a day before cocking/Firing the gun, do not be tempted to skip this stage as it will allow the seal to "mould" to the barrel shape/size and give a good fit, this procedure is well worth the effort and will pay dividends on how the gun fires and feels.
These are far better with the leather as they also damp the piston, I have used a mk3 with a ptfe seal and it was horrible, very harsh recoil and pistol slap.

Replace ALL parts of the seal assembly including the bolt and washer. Part No: AR20 from John knibbs and Titan leather oil to soak it.. Chambers do similar, complete seal and treatment oil should be around £20 altogether from either."


[NB: i've gone the 'Knibbs Part AR20' route - will let you know how it turns out but won't be able to do until after next weekend.]

[chieffool]

just to complete this: FOR THOSE ABOUT TO ATTEMPT THIS ... it really IS easy.
Have a plastic dish - best is a small tupperware with lid: Don't lose anything and easier to clean/rinse items.

You might need: a good selection of screwdrivers with decent/sharp flat heads. Check your 'choice' around on the screws around the outside of the gun - if you have enough to fit all eventualities, then all will be OK.
ALSO: old cloth down on wherever you will be working. Do not do this anywhere near carpet - old bits of dry grease flick everywhere.
WD40 (with a nozzle tube) and gun grease.
A torch.
Selection of old toothbrushes, or bronze brushes - NO steel bristles.
Lots of old cloth (it will be dirty/greasy)

1. Remove rifle from stock: screws either side of the breech, and the two screws on the trigger guard. Remove. Be careful (old gun) so you don't chip anything.
2. The Breech is where the pellets go in. Undo the two screws on LHS to remove the oval plate. Inside is a small spring (remove so you don't lose it). You can leave or remove the tap swivel if you want. Removing the plate exposes the screw which holds the underlever in place. Remove the screw and remove the underlever mechanism (jointed arm). The end of the underlever fits under the spring section and engages with the piston.
3. There is a large 'nut' which projects out about 1 cm, positioned in front of the trigger. The trigger mechanism is housed in the whole rear section which will undo when this nut is removed. The trigger section is threaded onto the rear of the rifle (about 15 turns) so it is quite safe to remove the nut. Nothing is going to fly off. REMOVE by turning CLOCKWISE (THIS IS A LEFT HAND THREAD). NB: The Nut is The 'receiving end' for the long trigger guard screw, and its main function is to anchor the trigger mechanism in place after the whole housing has been unscrewed.
4. Now start to undo the whole trigger mechanism. It may have old/compacted grease in there so a little squirt of WD40 won't go amiss. You can see the threads as it undoes so no surprises as you get towards the end.
BEFORE you reach the end, fold over an old cloth and place on floor. Stand rifle carefully on end with back of trigger mechanism pointing up. Grab the barrel in front of the breech (you will find the 'curve' where the underlever has been removed a good comfortable resting position) and lean against the gun barrel pushing down. This is so you can undo the last of the trigger housing thread without the mechanism popping off the end as the pre-load on the spring is about 2 inches. Don't worry - it really isn't THAT powerful). The Trigger mechanism should then unscrew the last turns without popping out and ease off.
5. You don't need to strip the trigger mechanism to get at the spring, piston, washer etc - so unless it needs it - DON'T.
6. Pull out the rear spring guide (3inch tube with a washer attached which allows the piston arm to slide through and engage with the trigger).
7. Pull out the spring
8. slide out the piston (may need the reverse end of the toothbrush to push it out).

STRIPPED!
The hard part is now cleaning, degreasing, oiling, etc. My washer had disintegrated years ago. Old bits of leather everywhere - yet miraculously the internal surfaces were clean, unscoured or pitted, and everything cleaned up nicely. I had a difficult time getting the old recessed metal washer/nut and remains of the leather off - but i followed the notes (as per posted before this) re shaping dry, soaking, etc and all seems fine.

NB: Shaping is best done by putting the new replacement leather washer (which comes with a new machine screw and recessed metal cup washer as a set) into a drill. Use sand paper. Do a little bit at a time, and keep checking for fit.

I also suggest you dry-test the trigger to check how well it is engaging. Just push the piston end into the trigger housing (obviously orientate it so the long slot the length of the piston cylinder is pointing down so that the end of the piston rod clicks into place correctly with the trigger). just pull on it and hopefully the trigger is holding until you pull the trigger to release. The action should be safe and positive. Engage again and give it all a bit of a gentle wiggle while pulling. If the trigger still holds, then all is definitely safe.

NOTE: apparently if you pull your piston too many times you can go blind!

CLEAN, regrease, oil and voila!

If anything else crops up..... then just raise it on the Forum....
and as if by magic, someone (usually lots of someones) will appear with the solution!

[chieffool]

ONE FINAL NOTE:
although the old spring came out easily enough.... it took all of my 17 stone bearing down to get the new one back in!

best way: have the rifle pointing down onto something soft/appropriate. In my case i used an old cloth folded over several times (while working on a wood floor). This way you can place palm of hand onto the end of the trigger housing, and bear down with your body weight while slowly turning the gun under to engage the thread and screw it on.

Have had to remove twice to check washer.... haven't lost any teeth yet!

[flatrajectory]

I am guessing that you have fitted a Titan mainspring if it takes all of your weight to compress it. If so, I feel that your mk3 is now oversprung. Is it hard to cock...? Does it feel harsh when you shoot it...?.
If the answer to these questions is yes then I suggest you replace it with a softer spring before you wear out the rifle or yourself.
Just trying to be helpfull. The standard mk3 mainspring should have about 30mm of preload and I can easily compress it, and I am a 10 stone weakling.
Regards,
Pete.

[Dan944]

Excellent advice here! Well done guys

I can vouch that a leather piston seal will give you the nicest shot cycle. I have actually gone down the modern path of a synthetic piston seal on my mk3 and all the bits that went with it, and yes it does shoot nice and very consistent....... But...... I am thinking of changing back to leather as not so long ago shot a old friends resently reseated leather piston sealed mk3 and believe me he's no tuner, but the thing shot a little smoother than mine and was also a couple of ftlbs higher than mine also.

I believe the leather parachute seal, flears more to give you a much better seal and hence better smoother shot cycle along with a bit of cushioning at the end of cycle.

I'm no expert on leather seals which is why I went down the modern path as I'm good with modern tuning, I even adjusted stroke because cylinder was a little shot and needed honing so hence me experimenting on mine.

I would definitely keep it as original and give it a new heart, with all this great advice from these guys, you will have a lovely example once done in sure.

Happy shooting
All the best
Daniel