Webley Mk3 (serial 9350) - Piston Washer Advice

[chieffool]

I'm actually going to put the old knackered spring back in. Both the leather washer set (part: AR20) and spring (part: AR40 ) came via John Knibbs International
http://www.airgunspares.com/store/ca...EY/Webley-Mk3/

BUT: whereas the leather seal has been a great success (i took ages to carefully and lovingly sand and shape, soak, fit, etc)...
...the spring does not seem 'right'. In comparison it feels Harsh, slammy, noisy. And i don't understand why.

Weirder than that: the old spring i took out (29 coils) only measures 220mm, and produces on my combro crono 434-438 fps, @6.3/6.7 ft lbs. This was the reason i decided on replacing it.

BUT: The new spring (which i didn't measure, but which is definitely longer) is only producing 367-371 fps, @4.78/4.90 ft lbs.

I've stripped it out twice (after a few pellets) to check nothing had happened to the washer, and it feels really good and positive compression when you push it in by hand. But something is not right, and realistically only the washer and spring seem likely candidates.

I only want it as a treasured garden plinker, but i'd like to see the old girl performing a little better. I thought perhaps 9.5 would be a realistic target.

How can you put a stronger spring in and get a 'weaker' result. Don't seem natural.

SUGGESTIONS? (I'm trying to think of all the really basic stuff as well so i can check for any literal mistakes i may have made)

Meantime i'm going to do the sensible thing and leave it in the bag while i consult the various orackles available through this board....
....sort of 'airgun ouija'

[Dan944]

Remoove piston, and shine a light in there and clean out and make sure there are no scores, could even be out of round and have sealing problems as mine did? This was common on these as they were shot alot with excess oil and constantly dieseling causing a bulging cylinder. So could be that your new seal is not supple enough to flear and seal the serfacr properly.

What to do first is have a look as I said a above, then put the original seal back on and with the new spring as it is and re crono. If power goes up it back to original power or more than you have now, then you have a sealing issue that you need to address first. Weather it is just the cylinder is as I mentioned above or your new leather seal is too sanded it not soaked and soft enough.....?

This is your first place to look. It could be oversprung but it gets more and more technical and for the power you have discribed, you really need to look into the advice I've mentioned first and go from there.

If bore looks good try pushing the piston down slowly by hand and feel any noticeable tight or loose spots as it slides down. It's hard to tell sometimes especially if your not used to the feeling, but the only proper way is to measure with the right tool which not even I had but I could feel mine was bulged and just new through trying to tune it through experience.

After you have done this we will go through possible tap leakages which could also be a factor?
Daniel

[chieffool]

I got a PM from a kindly member who sent me a suggestion. I think he PM'd to avoid embarrassing me with an obvious suggestion to test, but i really don't mind being embarrassed, so have repeated his suggestion ref COMPRESSION, and my (possibly daft) response as do want to solve this.

HIS SUGGESTION (:

How to check Check compression

1. Put tap in firing position
2. Cock rifle
3. Turn tap to load position
4. firmly hold underlever fully cocked...
5. ...Pull trigger to control return of underlever back to rest
6. Slowly move the tap to firing position and listen for hiss of air release

A good seal will hold for quite a few seconds....


MY 'RESULT':

If I leave tap at 'load' and control underlever back to rest, i can hear the hiss as the piston returns, reducing swept volume to zero. Hiss lasts about 3 secs... and comes from pellet well with tap in load position. This shows that tap well is not a perfect airtight seal to air pushing out - but is it designed to be that good against the full force of the spring returning down the gun?

Afterall, the spring is designed to ''fire' the piston and seal against a tap in the firing position - and is normally pushing against a pellet (not a closed tap).

SO: does this show it is good enough?

NEXT: If i repeat the process, but this time compress the spring with tap in LOAD position:
- FIRST: There is no (or can't hear) noise of air being sucked in...
- BUT: if i flip tap to firing position there is a good hiss as air rushes into to the cocked piston volume.
In this case i am assuming this is because the tap in LOAD position is better at sealing against the lower pressure differential inside the piston chamber trying to draw air in because it is a dramatically easier task then trying to seal against the force of a compressed spring pushing the piston back to rest.


MY QUESTION: Is How Good should it be?

[chieffool]

Remoove piston, and shine a light in there and clean out and make sure there are no scores, could even be out of round and have sealing problems as mine did? This was common on these as they were shot alot with excess oil and constantly dieseling causing a bulging cylinder. So could be that your new seal is not supple enough to flear and seal the serfacr properly.

What to do first is have a look as I said a above, then put the original seal back on and with the new spring as it is and re crono. If power goes up it back to original power or more than you have now, then you have a sealing issue that you need to address first. Weather it is just the cylinder is as I mentioned above or your new leather seal is too sanded it not soaked and soft enough.....?

This is your first place to look. It could be oversprung but it gets more and more technical and for the power you have discribed, you really need to look into the advice I've mentioned first and go from there.....Daniel

EXCELLENT...
...will do later on this evening and report back
Cheers
Richard

[flatrajectory]

Chieffool,
Did you not read my post higher up this page regarding the mainspring....???? Did you buy a Titan spring from mr. Knibbs...??? If so take it out immediately as they are way to strong for the mk.3.
you need to get an original spec spring.....try Protek supplies.

Pete.

[chieffool]

Chieffool,
Did you not read my post higher up this page regarding the mainspring....???? Did you buy a Titan spring from mr. Knibbs...??? If so take it out immediately as they are way to strong for the mk.3.
you need to get an original spec spring.....try Protek supplies.

Pete.

Many thanks for pointing out. I hope I haven't completely misunderstood your post.

YES: i did get the spring from Mr Knibbs. It is described as:
Webley Mk2 & Mk3 Mainspring Part No. AR40 Anschutz 250 280 335 & Haenel Model IV E


After reading your post i called them. The Guy I spoke to (who seemed knowledgeable) said the springs were made for them and correct for the gun. Got him to measure and count the coils (x29) which is the same as the old number of coils on the one i took out, though the old one is (now) only 220mm long. I'll measure the 'new' one when i swap over as want to take some more measurements with the old one in.

IS THE SPRING THEY'VE SENT ME SUPPLIED BY TITAN?

[flatrajectory]

Generaly, mr Knibbs sells only Titan branded springs, which may well be the same length etc. as original spec but as many will testify they are high tensile and very stiff.......too stiff for a vintage airgun. From the description of your effort required to get it in the gun I am guessing that this is what you have. Both the Webley mk3 and the Airsporters will give better power with a softer spring ,providing the rest of the rifle ,i.e. piston seal and tap are in good order.
No harm at all in trying the old spring.
Pete.

[deejayuu]

Chieftool. The cat's away so had a little play with compression checks
i) Airsporter good "vacuum" seal but loses all compression in a second or two
ii) Mk lll early 60's Vacuum good compression held at least 30 secs
iii) Mk lll mid/late 50's a bit neglected vacuum good compression held 15 seconds

They haven't been handled or shot for some time.
Will chrono then massage the internals before re chrono.

Results on here if interest shown

[chieffool]

Generaly, mr Knibbs sells only Titan branded springs, which may well be the same length etc. as original spec but as many will testify they are high tensile and very stiff.......too stiff for a vintage airgun. From the description of your effort required to get it in the gun I am guessing that this is what you have. Both the Webley mk3 and the Airsporters will give better power with a softer spring ,providing the rest of the rifle ,i.e. piston seal and tap are in good order.
No harm at all in trying the old spring.
Pete.

Have just spent an interesting chat with Vic at Protech. What a nice guy...
...he says (sadly) they now source all springs for MK3 from same supplier as Mr Knibbs....
Agrees they are 'harder/stiffer' spring, and suggested try taking off 1 coil at a time to see how/if it improves (with washer behind, etc).

Whole new ballgame - must check on the 'hows/mustdos/etc'. But i have dremel, diamond wheels, grinders, etc - and should be able to do slowly to avoid retempering any tips from getting stuff to glow by mistake.

ANY COMMENTS/HINTS/THOUGHTs?

[chieffool]

Chieftool. The cat's away so had a little play with compression checks
i) Airsporter good "vacuum" seal but loses all compression in a second or two
ii) Mk lll early 60's Vacuum good compression held at least 30 secs
iii) Mk lll mid/late 50's a bit neglected vacuum good compression held 15 seconds

They haven't been handled or shot for some time.
Will chrono then massage the internals before re chrono.

Results on here if interest shown

15 secs!!!!! hell-buggermesidewayswith-a-tin-can..... i'm not even close!!!!!!
3 secs - that puts me in the same range as your airsporter in item 1), so would be very interested to see chrono results for all anyway.

Meanwhile: i've ordered another type of washer (leather again) via VIC @Protech after long chat with him about this AND the fact that they also only stock Titan springs for Mk3s (ie same as Mr Knibbs where i got my recent replacement).

[deejayuu]

Well, well surprising, to me, results on the chrono!! Same pellets in each, five shot average
Airsporter poorest compression. fps 560
Mk lll '55 good compression fps 460
Mk lll '63 excellent compression fps 430

Conclusion based on cocking effort, and pure fantasy, it's all in the spring!!

[flatrajectory]

Don't worry too much about the ' 3 second' leak test. Remember the air can also escape past the piston seal ,if it is a poor fit,just as much as it can leak past the loading tap. But.....when you actualy fire the rifle the piston seal will flare slightly to improve the seal and ,as you have guessed, due to the speed that the firing cycle happens I doubt that a slight leak at the tap will affect velocity very much. You can improve the tap leakage by coating it in thick grease before insertion.
I honestly believe that your rifle is oversprung , so in the absense of a softer option you can try shortening yours a coil at a time. The problem with that is........shortening a spring makes it stiffer but it does reduce preload, so worth a try until you can find a softer spring.
Pete.

[thisisdonald]

Ill be interested in this thread as well.. I too have a mk3 which seems hugely oversprung - I was told the spring was replaced about 8 years ago and hasnt done much shooting since then.
Its hard to cock, twangy, jumpy and generally not nice to shoot. Ive not had it apart yet - thats for summertime. A source for a nice soft spring would be good.

[chieffool]

TO ANSWER ALL RECENT POSTS IN ONE:

SPRING:
i'm looking. Both Protek and Airgunspares are now 'Titan' springs. Compared to my old spring (which looks like a 'grey' steel untreated surface) the springs (if truly the same) from these others are very shiny - almost coated? And obviously stiffer. If i find a source i'll Post (and PM anyone who has asked).

SEAL:
i have another alternative on the way from Protek at their suggestion. There seems to be a debate about hard leather vs softer (tapered?) leather. Don't know enough yet, but will post update when received and after trying.
[The alternative on the way is Protek part MPH3: http://www.proteksupplies.co.uk/piston-seals-etc.html]

COMPRESSION vs 'SEAL' (ie Tap Test) vs SPRING:
Many thanks for chrono results supplied. NOT what i was expecting.
I WOULD REALLY APPRECIATE IT IF A COUPLE OF OTHERS COULD SUPPLY any results for their guns?
[See Deejayuu posts #23 & #26]


"Its all in the spring":
I also agree with flatrajectory that the titan spare from Airgunspares means my MK3 is oversprung. It just feels wrong in every sense - noisy/gronky when you cock, twangy when you fire and moves. The pre-load is so pronounced (and such a fight to close) that it must mean when the spring has cycle through and returned to rest it is still (as so stiff) under quite a load.

I WILL try shortening (0ne coil at a time) to see what happens - and will post chrono results. May even keep cutting coils until the rest length is back to my old 'knackered' spring @220mm so i get a set of results to compare stiffness of one versus softness of other.

- but before that i'm going to swap it out and put in my old/softer spring so i can try out the different washer coming over from Protek.

Its obviously not ALL in the spring - but its going to be a balance between everything.
Dog Gammit.... thats the Fun Part!

[deejayuu]

Getting hooked on this now!
I have some spare springs in the "extensive parts store"
Will do some measuring/ spring rate comparison & see what's going on. Keep breathing!!

Chores come first