Webley Service power?

[Garvin]

What sort of power should a 3rd series Webley Service Mk2 produce in tip top condition please?

My .177 is producing only about 6ft/lbs despite the fact it has a brand new Chambers spring, a new piston ring and a new breech seal which gives a good tight fit when the bolt is closed. I greased the internals sparingly with moly. I expect power will increase a bit as it beds in but I was hoping for 8+ ft/lbs and I'm skeptical it will gain another 2 ft/lbs on its own, or am I wrong?

Any thoughts welcome.

[pennineway.fswo]

Hi Garvin
I have a couple of Mk11's, both in .22 cal.
One is shooting at about 9 ft lbs without dieseling. The other one has a healthier spring as it is certainly more difficult to cock and it is closer to 10.5 ftlbs. However this one does diesel but is still pretty consistent and groups well over 20 yards.
Both rifles seem more accurate than my Mk11 Airsporters, but are not as powerful.
I would have thought that a .22 with a good spring and piston ring should be around the 10 to10.5 ft lb mark and so a well run in .177 should be 8.5 or 9 ftlbs.
I am sure the power will go a little with use but 6 ftlbs does seem a little low considering a new spring has been fitted. How tight is the piston fit with the new ring and have you tried a variety of pellets through it ?
John

[Hsing-ee]

I think it might increase a bit with the piston-ring wearing in. On the other hand, the design is not very efficient and may do alot better in the 'Fat Man' calibre.

I am hoping that the 150 will get up to 8.5 or even 9 with running-in and the right pellet. The new piston ring was much firmer, even though the old one was sealing very well.

Try a mammoth plinking session and see what the Service does afterwards.

[Garvin]

a well run in .177 should be 8.5 or 9 ftlbs.

That's what I thought John, thanks. The piston seemed to be tight but not too tight, just right. I'll try some other pellets through it and see it that helps.

I think it might increase a bit with the piston-ring wearing in.

Try a mammoth plinking session and see what the Service does afterwards.

You could be right Alistair, I'll try putting a couple of hundred pellets through it and see if that helps.

[edbear2]

I have just rebuilt one of these as well...ultrasonic cleaned everything, honed the cylinder very lightly to help the ring bed in.......new ring, spring and barrel seal from Mr Knibbs (spring was a pretty close match, unlike the normal XS "cut 3 inches off and it may fit with a porta power" ones which I personally think are not the best for accurate and smooth shooting....I dont need to build up my forearms at my age......anyway, sorry to ramble, I will post the power/fps when I get it on the range, and do another after the obligatary 2 or three tins later......mine is .22 also, any recommendations regarding a good pellet please as a starting point?.....normally use wasps (old stock proper eley) or webley specials (ditto) in guns of this period..ed

[DCL_dave]

Hi Garvin,

Mine only produces about 7fpe in .22 with AA fields, but it is reasonably accurate and very pleasant to shoot at that power so i'll leave it alone for now...

One question, is the rear sight a friction fit in it's dovetail for windage? and do you just tap it over with a block of wood and a hammer to adjust?

[Phil Russell]

I serviced one of ours a little while ago. Can I assume you are using the leather breech seal provided by Chambers?

My original breech seal was a fibre washer mounted on a brass 'carrier'. I was disappointed in the Chambers leather seal as it was just a leather disc for about £5. I had expected a new unit akin to the one I replaced. Performance was quite poor with the leather seal despite the new spring. So I found another fibre washer and mounted it on the brass carrier. Performance leapt up to around the 8.5 ftlbs mark (.177).
Looking at the leather breach seal I did not think it would fit on the brass carrier so had fitted it without ... it seemed a good fit and to fill the recess well. Maybe it just did not.

Lubrication can be an issue as well. I was told the piston ring needs to be lubricated with oil, so I smeared a little car engine oil around it. Previous work had shown me that this was better than other lubricants with little or no dieseling.

Hope this helps.
Cheers, Phil

[coburn]

I'd suspect the pistol ring. I've had similar troubles with the Senior with its metal piston ring. Best mod I did was to replace this ring with a modern O ring. It worked wonders and I believe the idea was featured by Geoff Boxall in AGW donkeys years ago.

[coburn]

BSA used an o ring on the Mercury/Airsporter and Meteor for years with no ill effects so I think any decent neoprene O ring of the right diameter would do. I used to find one slightly undersized would give the piston a loose fit in the cylinder and give more power. The metal pistol rings were always too tight when new, however something else you can try is to file the gap on the ring open a bit, this reduces its size slightly when fitted allowing for a looser fit in the cylinder, dont over do it though.

[DCL_dave]

Dave I'm not sure about the rearsight. It certainly looks as if it's a friction fit and will move in the dovetail but I can't say I've ever done it because I only use the peep sight.

Thanks Garvin, I haven't been brave enough to take a hammer to the small rearsight yet

Perhaps i'm using the peepsight incorrectly? I've never used one before getting the service so I'm finding it difficult to consistently place the foresight post in centre of the circle of the peepsight oh well, keep practicing I suppose

[Garvin]

Thanks Garvin, I haven't been brave enough to take a hammer to the small rearsight yet

Perhaps i'm using the peepsight incorrectly? I've never used one before getting the service so I'm finding it difficult to consistently place the foresight post in centre of the circle of the peepsight oh well, keep practicing I suppose

You don't need to Dave, that's not how a peepsight works. The fact that you are seeing the foresight through that tiny hole means front and rear sights are already aligned. Forget about centring it precisely, just place the front post on the target and fire.

[DCL_dave]

You don't need to Dave, that's not how a peepsight works. The fact that you are seeing the foresight through that tiny hole means front and rear sights are already aligned. Forget about centring it precisely, just place the front post on the target and fire.

Ah!...so I'm trying too hard and making the whole procedure unduly complicated... I'll give it a go at the club later on today, thanks

[T 20]

Thanks gents for the extra ideas.

I have now tried a variety of (modern) pellets and the power level is not good with any of them.

Interesting criticism of the Chambers breech seal. It is a bit soft and deep for such a large recess without the rigidity of the brass tube. My Mk2 has a Knibbs barrel which has a narrow raised rim at the breech, presumably designed to enhance sealing. (As an aside, Mr Knibbs has a new batch of .177 barrels being finished now and will be charging around £160 each. )

Also interesting to hear about the o-ring. Has anyone else done this or know in which AGW issue GB looked at this mod? I have one of those Chinese-made o-ring assortments in the red plastic box, but I don't know if the shore rating is suitable for the inside of an air rifle.

Dave I'm not sure about the rearsight. It certainly looks as if it's a friction fit and will move in the dovetail but I can't say I've ever done it because I only use the peep sight.

Hi Garvin
When converting to an O ring piston seal I find a shore rating of 70 to be adequate. I buy quite a few assortment boxes of O rings each year for work and find most are 70 shore.
I have used these in everything from a HW 35 to a Relum Tornado with good results.
I always find it best to have both Metric and Imperial sizes available when attempting to find just the right size and fit for a piston.
I have never played with a service MK 2 but if it has two piston rings with a gap inbetween it could be worth fitting both grooves with an O ring and using the gap between them as a reservoir for silicon oil, this is what John Bowkett used to do on his O ring piston head conversions.

All the best Mick

[Garvin]

Hi Garvin
When converting to an O ring piston seal I find a shore rating of 70 to be adequate. I buy quite a few assortment boxes of O rings each year for work and find most are 70 shore.
I have used these in everything from a HW 35 to a Relum Tornado with good results.
I always find it best to have both Metric and Imperial sizes available when attempting to find just the right size and fit for a piston.
I have never played with a service MK 2 but if it has two piston rings with a gap inbetween it could be worth fitting both grooves with an O ring and using the gap between them as a reservoir for silicon oil, this is what John Bowkett used to do on his O ring piston head conversions.

All the best Mick

Thanks for this advice Mick, very useful. The Service has only one ring. Thanks also to Coburn for suggesting an O-ring in the first place. I will try it when I get some time and will report back.

[TopDog]

Hi all

Can certainly vouch for the superiority of the 'O' Ring. My Service Mkll was fitted with one when I bought it about 20 years ago, a previous owner of mine fitted one on a spare piston (original with brand new PB piston ring retained to be able to restore to original condition!) so it is very easy to compare.

The gun operates much more smoothly with the 'O' Ring as opposed to the PB piston ring when it all sounds a bit; well, agricultural.

I think that the piston groove may have been modified on this one which is probably why the original was retained.

These are very satisfying things to own and use.

BFN and happy airgunning - whatever the form!
David