Webley Xocet - run out of puff

[DS4IS]

Morning all and a happy new year!

A while ago a friend was complaining that his Webley Xocet was not performing as it used to. We put it across my chrono and found it was only pushing out about 5 FPE.

Having resprung and tuned a few springers I volunteered to sort it for him. I fitted a Titan kit from Chambers and generally gave it a thorough service including a bit of piston polishing, breach seal etc. only to find it was still only delivering about 5 FPE.

The spring I fitted seems almost identical to the old spring so I think it is the correct one and the preload is about 35mm which seems quite a lot to me but I understand it is about right for the Xocet.

I've checked through the compression chamber and transfer port and all seems to be good and the piston with its new seal seems to be a nice sliding fit so I'm at a bit of a loss as to why I can't get the power up to normal levels. I haven't tried adding preload washers yet but as it's so far down I'm not sure that a few washers would be enough.

Any thoughts?

[Phil Russell]

This is one of those situations which, while being a challenge, is also a pain. Not knowing exactly what you have tried (so forgive me if I suggest things you have tried) this is where I would start:
1. Check breech seal: with rifle cocked and loaded, place a bit of moist tissue over the breech area and shoot. A leak will send the tissue skywards.
2. Strip the rifle. With the piston in place in the cylinder seal the end of transfer port with finger and see if you get fair compression as you push the piston down. If the piston simply pushes to the end of the cylinder with little resistance then you have an air leak somewhere.
3. If you are convinced the piston seal is OK and is not too tight, then air must be escaping from somewhere else. I do not know the Exocet but have seen these issues on other rifles: Could air be escaping through the stock mounting bolt holes? I have seen the holes tapped too far and entering the transfer port. If in doubt, add oil to the hole and push piston down .. any leak will bubble the oil out. Could the end of the cylinder be leaking at a joint as seen on the HW35?
4. Is there any obstruction in the transfer port?
5. Could the spring be too strong? Most unlikely, but if you had a real struggle in fitting it then this may be a contibuting factor.
6. Try replacing the old bits one by one ... starting with the old piston seal.


Hopefully by a process of elimination you will find the cause.
Cheers, Phil

[ggggr]

Pretty much as Phil says. However, if your mate is convinced that the power was up before, then common sense says that a fault has developed rather than being in the gun from the start. With the power being so far down, it would suggest a leak somewhere.
I had a Webley hawk that was well down on power and that was leaking from the block that screws into the cylinder, but round the threads rather than the stock screws having been drilled too far. The strange thing I found is that the threads of this block only extend about 2 threads beyond the stock screw holes.
My first thoughts would be to see if the barrel is (1) clean, with no debris in the rifling (2) straight.
I,d then look to see if the barrel is meeting up with the breech seal ok and consider a little packing of the breech seal as an experiment.
Is the barrel plunger ok and the spring strong enough to stop the barrel opening a little on firing?
Then as the cheap option, flatten your old spring a coil or two and see if that helps.
To check for a leak in the cylinder end, try putting the last couple of inches in water and then push your piston down the cylinder with a piece of dowel and look for leaks. (you will need to bung up or keep your finger over the breech seal/ transfer port.)

[johnbaz]

Also

If the piston is slamming in to the end of the cylinder then it will be as stated, an air leak somewhere, if it's buffering OK then look to see if there's rust in the barrel
This will slow the pellet down loads but won't get the metallic bang of the piston hitting the cylinder end with no resistance..


Good luck with the fix



John

[DS4IS]

Thanks for your suggestions chaps, very helpful.

I figured that there is probably a leak somewhere, I'll try the things you've suggested.


Thanks again.

ATB Mark

[Gwylan]

Lots of good advice here, as said, check the lockup and breech seal. I always debut and polish the cocking slot, as this may nick a new seal when you slide the piston in. Must be leaking somewhere.

Gus

[DS4IS]

Well, there ya go. Breech seal it was.

I was fooled into thinking it must be ok because a) it was new and b) it seemed to protrude a little from the face of the breech and c) I am especially dim today. The actual lock up faces are hidden by the rear sight so there was no visible gap, but when I removed it and did the damp tissue test it was obvious that the seal was not sealing at all - especially when the tissue flew through the air when I fired it.

I packed out the seal with an old trimmed down seal and hey presto 11.3 FPE! I've ordered another seal but I think there's a problem because the slot it fits into is 4.7mm deep and the new seals seem to be about 4.5 to 4.6mm so it might need a more permanent packing solution (maybe I need to machine up a small washer to fit the breech seal slot to reduce its depth a bit). There is no movement or adjustment to be had in the barrel lockup but the gap is only a few thou anyway.

Thanks for the suggestions, especially as I should have thought of them myself

Mark

[johnbaz]

Mark

Find a small brass washer that with fit in the recess then fit the breech seal, that will cure it



Cheers, John

[Phil Russell]

Excellent ... pleased it was so simple.
As said, a washer is a good idea ... I believe some people have used an O ring to the same effect. I am sure some rifles from 'some' manufacturer were fitted with shims beneath the breech seal, but cannot remember which rifle it was. Maybe a Diana/Original.
Anyway ... happy you are sorted.
Cheers, Phil

[TonyL]

Sorry to jump in so late, been at the in-laws for dinner

Anyway, really glad that it's sorted and was a nice, easy fix.

Sometimes, it's so tempting to look for a problem that may not exist, which is much more involved.

This is another reminder to always check the basics first before embarking on more complicated, more involved work.

Well done, glad you're sorted.

Phil, like the idea of oil in the cylinder and then compress to check for leaks. Any particular grade of oil?
Would a thinner oil be better?

[bighit]

kerosene would be better than oil as its thinner so would show up leaks that oil may seal

[walrus1#]

The breech seals on quite q dew springers are slightly small I found. So as a fix for the problem I use a ring of solder that fits in the groove and is then melted into place with a torch (careful not to over heat as this will ruin the bluing) but as a fix it is first class.

[evert]

Have had great success using dental floss for shimming up breech seals(recommended several places on the net). Easy to apply, and easy to adjust for thickness.

[Phil Russell]

Just to clarify the 'oil' tip: I use this to detect any possible air leak into the stock mounting bolt holes. add a few drops of oil into the mounting bolt hole then push the piston down by hand. An air leak shows by oil bubbling out. I did not intend to give the impression I added oil to the cylinder. Which oil? I use any light oil, whatever is to hand, usually a 3 in 1 type of from a 'gun oil' dropper bottle. If the test shows a leak the oil needs cleaning out before remedial action is taken. If no leak .. you now have nicely oiled threads.
Cheers, Phil

[TonyL]

TA for clarifying that, Phil.
I was thinking more of the 35 and the potential of leaky brazing on an earlier one.

Ciao,

Tone.