Webley Mk3 issues

[jirushi]

Hi,
I am doing some experiments with my recently acquired Webley Mk3 and some Mk3 parts. Trying to find out how smooth I can get it, with a decent power output (hopefully about 9 or 10 ft/lbs). I am experiencing a few issues. Some info first.

The assembled action on the photo is a .22, from Fleabay. The barrel has just been recrowned and I had the scope rail fixed with 4 screws. My friend did a good job.
The other action is a .177.

I am concentrating on the .22. It has a new Protek spring. A delrin spring guide. I fitted a steel beer can piston sleeve.
Polished the inside of the cylinder, cocking slot, cocking shoe, sears, outside touching points of piston, top and bottom of spring, outside of spring.

The leather piston seal was perished. I replaced it with a 28 mm synthetic Vortek seal with adapter. When my gf puts her finger on the muzzle and I cock the rifle, there is a vacuum (I did check and double check that the gun was unloaded ). So the seal seems to work. I have also bought a new leather seal from Knibbs. I'd like to use the synthetic seal though, as I find synthetic seals more consistent and I do not have to worry about oiling them.

I know that the large transfer port might be an issue when using a synthetic seal. But.....: I am only getting 5.7 ft/lbs with 15.89 gr JSB Exact .
I've also tested without piston sleeve, with factory spring guide and old but straight spring > still low power. Whilst it takes a lot of force to cock the gun. This puzzles me. Perhaps the seal isn't as efficient as I think.

It might all seem quite over-the-top or even sacrilegious to do these things with a Mk3, but I like a bit of tinkering. Although I have a feeling that I am wasting my time and money on this gun, as my 50 pound tuned Meteors shoot harder and nicer with much less cocking effort and a better balance, I would like to see this project through.
(Btw the later stock was on the .177 gun I bought - the one on the third photo. The earlier stock is from Fleabay. I am looking for a second type trigger so I can use the earlier stock, which I find very beautiful).

I have a feeling that sleeving the transfer port to about 3 mm would be the solution, but I would greatly appreciate your thoughts/input.
Also on how to sleeve this transfer port hehe.

[deejayuu]

http://www.airgunbbs.com/showthread....nsfer-port-etc

[jirushi]

http://www.airgunbbs.com/showthread....nsfer-port-etc

Thank you. That's interesting. I was thinking about making a brass insert, with a 3 mm hole. And fixing it with Loctite. But your method is certainly more refined.

Do you know how "long" the Mk3 transfer port is? And what its diameter is? (.22" action). Many thanks

[deejayuu]

Thank you. That's interesting. I was thinking about making a brass insert, with a 3 mm hole. And fixing it with Loctite. But your method is certainly more refined.

Do you know how "long" the Mk3 transfer port is? And what its diameter is? (.22" action). Many thanks

The original TP diameter is the same as the rifle calibre. Factory process to ream the tap in situ. involved working from comp. tube end.
This, comically, can result in a pellet being drawn from tap to cylinder if cocked after loading. Slack pellets have been known to fall in if rifle held vertical.
Ours measured 19 mm x 5.5 mm (.22 really) with limited tools.
http://www.airgunbbs.com/showthread....pinions-please

[andrewM]

I have found Superdomes and H&N Sniperlight to perform well in mine.

The link from Deejayuu was most interesting. Within that link was a further link which is worth reading in terms of the posts therein:

http://www.airgunbbs.com/showthread....r-loading-taps

I also noticed these posts:


Prof51mtw
Good Morning Mick: Yes, the compression ratio or, more specifically, the peak cylinder pressure will have an effect on the optimum TP size. Whether lubricant vapour combustion is present also has an effect, as Jim has just pointed out to me, citing the fact that Weihrauch reduced the size of the TP on the HW55 when moving over to plastic piston seals.
Mike

T20 Super Moderator

Thank God for that --- I thought I'd been imagining it.

As Jim has pointed out Weihrauch changed from a 4mm transfer port to a 2.8mm port when they went from leather to synthetic seals --- so in effect they doubled the static compression ratio.

I'm finding leather seals like to work at a sub 200:1 compression ratio and synthetic seals and O rings work best at 300 : 1 upwards.

The Webley MK3 has one of the lowest compression ratios I have found at 80:1, I am considering fitting a Diana 52 piston seal to one of mine and then sleeving the transfer port down to 2.5mm --- on paper this should make it a bit more user friendly.

Unquote.

This is really into the technical detail but also sheds further helpful light on the subject.

A

[jirushi]

I have found Superdomes and H&N Superlight to perform well in mine.

The link from Deejayuu was most interesting. Within that link was a further link which is worth reading in terms of the posts therein:

http://www.airgunbbs.com/showthread....r-loading-taps

I also noticed these posts:


Prof51mtw
Good Morning Mick: Yes, the compression ratio or, more specifically, the peak cylinder pressure will have an effect on the optimum TP size. Whether lubricant vapour combustion is present also has an effect, as Jim has just pointed out to me, citing the fact that Weihrauch reduced the size of the TP on the HW55 when moving over to plastic piston seals.
Mike

T20 Super Moderator

Thank God for that --- I thought I'd been imagining it.

As Jim has pointed out Weihrauch changed from a 4mm transfer port to a 2.8mm port when they went from leather to synthetic seals --- so in effect they doubled the static compression ratio.

I'm finding leather seals like to work at a sub 200:1 compression ratio and synthetic seals and O rings work best at 300 : 1 upwards.

The Webley MK3 has one of the lowest compression ratios I have found at 80:1, I am considering fitting a Diana 52 piston seal to one of mine and then sleeving the transfer port down to 2.5mm --- on paper this should make it a bit more user friendly.

Unquote.

This is really into the technical detail but also sheds further helpful light on the subject.

A

That's great Andrew, thank you.
Great info. Very technical, yes. But with the tp measurements at hand, it shouldn't be too difficult to make a brass insert (is that the word?) to fit the tp, and then drill a 2.8 or 3 mm hole in it. Degrease the tp, some red Loctite on the insert, and then a long rod to place it in the tp. Luckily I know someone who is good with metal work haha.
Would be a lot easier than tapping the tp.

[thisisdonald]

Right... I've got an old banger of a mk3 here.. how do I tap all the way down the compression tube? Do I need to make an extended tap holder or is there a nifty trick to it?

[deejayuu]

Right... I've got an old banger of a mk3 here.. how do I tap all the way down the compression tube? Do I need to make an extended tap holder or is there a nifty trick to it?

A square drive/8 point socket on extensions worked OK for me.

[jirushi]

The original TP diameter is the same as the rifle calibre. Factory process to ream the tap in situ. involved working from comp. tube end.
This, comically, can result in a pellet being drawn from tap to cylinder if cocked after loading. Slack pellets have been known to fall in if rifle held vertical.
Ours measured 19 mm x 5.5 mm (.22 really) with limited tools.
http://www.airgunbbs.com/showthread....pinions-please

Thanks to all above for the input. @ Modski 66 and Geezer, will get some RWS Superpoints and Superdomes. I have Hobby's for my Crosman 400 (still not the right pellet for that multishot mechanism, just to go off-topic a bit). Will give them a go.

Very good info here, deejayvuu. What an enormous transfer port If this were a pcp, you could shoot deer with it
19 mm long - good heavens. Thank you for the link

[Modski66]

My .177 Mk3 is currently in bits in the shed as I am gluing shut the cracks in the stock and smoothing out the internals.
So far, I have done similar things to you, but also cut some PTFE rings for the ends of the spring from some 0.5mm sheet off the 'bay.
I am keeping the leather seal as it is in pretty good condition, apart from being a bit dry - currently soaking in some SAE30 oil.
All the trigger contact points are now polished, I just need to clean out the main tube. I too am curious about the transfer port, what effect reducing it has, and how on earth to acomplish it down the end of a narrow tube!

Cheers,

Mark.

[jirushi]

My .177 Mk3 is currently in bits in the shed as I am gluing shut the cracks in the stock and smoothing out the internals.
So far, I have done similar things to you, but also cut some PTFE rings for the ends of the spring from some 0.5mm sheet off the 'bay.
I am keeping the leather seal as it is in pretty good condition, apart from being a bit dry - currently soaking in some SAE30 oil.
All the trigger contact points are now polished, I just need to clean out the main tube. I too am curious about the transfer port, what effect reducing it has, and how on earth to acomplish it down the end of a narrow tube!

Cheers,

Mark.

Nice! What type of Mk3 have you got? I'd love to feel the difference between 1st, 2nd and 3rd type triggers. Apparently the 2nd type are best (although nobody seems to like any of the Mk3 triggers very much...).

Btw one explanation of my low power issues could be the pellets I'm using. Should have known that this old barrel needs 5.6 mm or at least 5.55 mm pellets. Will have to find some.

[rockdrill]

Nice! What type of Mk3 have you got? I'd love to feel the difference between 1st, 2nd and 3rd type triggers. Apparently the 2nd type are best (although nobody seems to like any of the Mk3 triggers very much...).

I have an early Mk3, serial no. 31:



This has the 'double pull' i.e. two stage trigger of Diana design and I also have a later Mk3 with the second type trigger with the really curly trigger blade, but I don't have a picture of that one to hand.

The double pull trigger to me is an excellent trigger, well ahead of its time and better than a lot of current triggers on springers. I have to say I really like it.

The second type trigger is not as refined but is still a respectable trigger.

The later triggers just don't seem to be as good.

[jirushi]

I have an early Mk3, serial no. 31:



This has the 'double pull' i.e. two stage trigger of Diana design and I also have a later Mk3 with the second type trigger with the really curly trigger blade, but I don't have a picture of that one to hand.

The double pull trigger to me is an excellent trigger, well ahead of its time and better than a lot of current triggers on springers. I have to say I really like it.

The second type trigger is not as refined but is still a respectable trigger.

The later triggers just don't seem to be as good.

Wow what a beautiful gun!
Love that first type trigger.
Good to read a positive experience with Mk3 triggers. I think a lot of what I have read about them is based on hearsay.
Nice stock too. Those early stocks are usually quite plain like mine, but this one has some nice figuring.

[Benelli B76]

Louis, is the seal too tight a fit in the cylinder ? Also is it a thin lipped parachute seal design ? Regarding the hard cocking I have found a strange phenomena on a lot of old MK 111 rifles that the cocking lever is very tight in its hinge bracket, giving a lot of resistance. Disconnect it from the piston and see if it swivels easily. I have had to shave off some metal to make them move smoothly.

Baz

[jirushi]

Louis, is the seal too tight a fit in the cylinder ? Also is it a thin lipped parachute seal design ? Regarding the hard cocking I have found a strange phenomena on a lot of old MK 111 rifles that the cocking lever is very tight in its hinge bracket, giving a lot of resistance. Disconnect it from the piston and see if it swivels easily. I have had to shave off some metal to make them move smoothly.

Baz

Thank you Baz. The seal isn't too tight. It feels good, when moving the piston up and down in a partly assembled state (without the spring).

But still, I wonder if it's too loose. The Webley cylinder probably isn't exactly 28 mm, as it will have an imperial size? Last time I measured I read 28 mm, but I'm not sure how precise I was.

Here's a photo of the top of the seal (a bit blurry sorry). It's pretty tough material. I'll order a 29 mm Lightning SE seal and see if that is any better. But I think I should try 5.6 mm pellets first (if I can find them...).

Yes the cocking lever is tight in its hinge bracket. But certainly not that tight that it would explain the huge cocking effort. I think that's down to the new spring, and 2 steel washers that I put on both sides of the folded top of the steel piston sleeve if that makes sense. But mostly the short cocking lever.