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Thread: My Mercury Ratting Rig

  1. #16
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    Quote Originally Posted by Shed tuner View Post
    best airsporter tune is to chop the spigot, thread m8, stick on adapter for a diana 28mm seal, job done. +5mm stroke and a seal that actually works, transforms them.
    I've done that one, Jon, but I want to go further.



    All the best Mick

  2. #17
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    Quote Originally Posted by T 20 View Post
    There's the thing, James.

    The Airsporter and Mercury has the same bore and stroke as my Original 35 which is such a nice firing cycle it inspired me to have another look at my BSAs.

    As the Mercury uses the same piston as the MK4-6 Airsporter, I'm hoping to upgrade my two Airsporter S when I've settled on a tune for the Mercury.



    All the best Mick
    Quote Originally Posted by Shed tuner View Post
    best airsporter tune is to chop the spigot, thread m8, stick on adapter for a diana 28mm seal, job done. +5mm stroke and a seal that actually works, transforms them.
    Any idea how the TP dimensions may compare between the Airsporter and Mercury, gents?

    Also, I guess the tap on the loading tap versions of the Airsporter will drop the SCR drastically?
    THE BOINGER BASH AT QUIGLEY HOLLOW. MAKING GREAT MEMORIES SINCE 15th JUNE, 2013.
    NEXT EVENT :- May 17/18, 2025.........BOING!!

  3. #18
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    yeah, the airsporter benefits from a sleave down too.. never looked at a merc port ?
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

  4. #19
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    Quote Originally Posted by simona View Post
    Those pheasant pictures are something else - they remind me of a magic lantern investigation into whether a galloping horse ever looses contact with the ground.
    They remind me of Hilda Ogden's wall.

  5. #20
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    Hi Mick

    What is the scope you have on the Ratter?

    Cheers
    Matty
    Opportunity is missed by most people, because it is dressed in overalls and looks like work.

  6. #21
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    Quote Originally Posted by T 20 View Post
    Yes, evert.

    The late Airsporter/Mercuries had a cutout in the top of the piston skirt to clear the Maxgrip scope rail lugs.
    I'd prefer to keep the full skirt to retain the option of fitting a bearing if I feel the gun needs one.



    All the best Mick
    Probably wise to keep the full skirt. Mine had started scraping out grooves in the cylinder before I got it.
    Dont know if it is the original piston as the gun doesn't have the Maxigrip, and other parts had been switched on the gun too.
    Its better now with a deburr and proper lubrication, but the full circumference piston would be best.
    Too many airguns!

  7. #22
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    Quote Originally Posted by TonyL View Post
    Any idea how the TP dimensions may compare between the Airsporter and Mercury, gents?
    No idea on the Airsporter yet, Tone, but what I can give you are the standard Mercury dimensions :-

    Cylinder Bore X Stroke = 28mm X 65mm (1.1" X 2-9/16")

    Available compression cylinder = 28mm X 95mm

    Piston weight = 320grams

    Transfer Port = 3mm X 11.2mm

    Available Spring room when cocked = 110mm


    The only difference on my rat gun are the stroke at 70mm and a piston weight of 314 grams.

    The spring I removed was a 33 coil Spring with 3.1mm wire.

    Another problem which showed up was the fact that the end wall of the cylinder has a hemispherical section machined from the centre of it.
    I don't know if this is supposed to be there or is a machining cock up at the factory, whichever it is it creates a little more work as I'll have to make a P38 casting of the cylinder end wall and machine the piston head to match.

    That's about as far as I'm going to get today while I stare at the piston and think about the job, but I have a good idea which way this is going to go --- new piston.




    All the best Mick
    Last edited by T 20; 04-06-2022 at 07:25 AM. Reason: Compression cylinder

  8. #23
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    Quote Originally Posted by MattyBoy View Post
    Hi Mick

    What is the scope you have on the Ratter?

    Cheers
    Matty
    Hi Matty --- long time no see.

    The scope is a Kassner 4 X 40 PA with TV screen view and is basically scrap, I got it for free as the crosshairs had snapped.
    I took the scope apart and soldered the thinnest wire I could find in there as new crosshairs.
    Unfortunately the wire wasn't thin enough, so now when you look through the scope it's like looking at a pair of crossed fence posts --- looks a bit like the Klan are in town.
    I know this doesn't sound too good but at short range in low light conditions when ratting my homemade crosshairs work well.



    All the best Mick

  9. #24
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    Quote Originally Posted by evert View Post
    Probably wise to keep the full skirt. Mine had started scraping out grooves in the cylinder before I got it.
    Dont know if it is the original piston as the gun doesn't have the Maxigrip, and other parts had been switched on the gun too.
    Its better now with a deburr and proper lubrication, but the full circumference piston would be best.
    I had an Oldschool HW85 like that, Evert.

    The cutout has to be there to clear the scope rail but nobody had ever smoothed the corners of the slot out so it marked the top of the cylinder.



    All the best Mick

  10. #25
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    Quote Originally Posted by T 20 View Post
    No idea on the Airsporter yet, Tone, but what I can give you are the standard Mercury dimensions :-

    Cylinder Bore X Stroke = 28mm X 65mm (1.1" X 2-9/16")

    Piston weight = 320grams

    Transfer Port = 3mm X 11.2mm

    Available Spring room when cocked = 110mm


    The only difference on my rat gun are the stroke at 70mm and a piston weight of 314 grams.

    The spring I removed was a 33 coil Spring with 3.1mm wire.

    Another problem which showed up was the fact that the end wall of the cylinder has a hemispherical section machined from the centre of it.
    I don't know if this is supposed to be there or is a machining cock up at the factory, whichever it is it creates a little more work as I'll have to make a P38 casting of the cylinder end wall and machine the piston head to match.

    That's about as far as I'm going to get today while I stare at the piston and think about the job, but I have a good idea which way this is going to go --- new piston.


    All the best Mick
    Excellent information as always, Maestro.

    Maybe nice to post those vital stats in Brucie's Bore, Stroke & SCR thread, if you don't mind?

    Nicely enough dimensioned TP, methinks?

    Hemispherical section in the cylinder end (head?) - does it think it's an internal combustion engine? Maybe this was where the term "dieseling" originated from?

    Hope you get that addressed. Correcting that lost volume should improve efficiency no end.
    THE BOINGER BASH AT QUIGLEY HOLLOW. MAKING GREAT MEMORIES SINCE 15th JUNE, 2013.
    NEXT EVENT :- May 17/18, 2025.........BOING!!

  11. #26
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    Quote Originally Posted by evert View Post
    Probably wise to keep the full skirt. Mine had started scraping out grooves in the cylinder before I got it.
    Dont know if it is the original piston as the gun doesn't have the Maxigrip, and other parts had been switched on the gun too.
    Its better now with a deburr and proper lubrication, but the full circumference piston would be best.
    Quote Originally Posted by T 20 View Post
    I had an Oldschool HW85 like that, Evert.

    The cutout has to be there to clear the scope rail but nobody had ever smoothed the corners of the slot out so it marked the top of the cylinder.



    All the best Mick
    Now, someone dud tell me about that "back in the day". It may have even been Dave and Ivan at Venom. And it's the reason why I never fancied the old school 85. Possibly why I didn't keep my Challenger for long, either.
    THE BOINGER BASH AT QUIGLEY HOLLOW. MAKING GREAT MEMORIES SINCE 15th JUNE, 2013.
    NEXT EVENT :- May 17/18, 2025.........BOING!!

  12. #27
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    Quote Originally Posted by T 20 View Post
    Hi Matty --- long time no see.

    The scope is a Kassner 4 X 40 PA with TV screen view and is basically scrap, I got it for free as the crosshairs had snapped.
    I took the scope apart and soldered the thinnest wire I could find in there as new crosshairs.
    Unfortunately the wire wasn't thin enough, so now when you look through the scope it's like looking at a pair of crossed fence posts --- looks a bit like the Klan are in town.
    I know this doesn't sound too good but at short range in low light conditions when ratting my homemade crosshairs work well.



    All the best Mick
    Reminds me of the nasty, knackered looking scope atop my equally cosmetically challenged Supersport, Mick. And that's another ratty looking potentially ace little ratter......The stock is truly distasteful after being "customised" by some previous owner. But it's actually really ergonomic and handles well. On the scope, the windage turret has some nasty cover hammered on. And the elevation turret is hanging off. But it adjusts okay. Sight picture is excellent and I really like the simple single post (German sniper?) reticle. The quintessential barn / ratting gun.
    THE BOINGER BASH AT QUIGLEY HOLLOW. MAKING GREAT MEMORIES SINCE 15th JUNE, 2013.
    NEXT EVENT :- May 17/18, 2025.........BOING!!

  13. #28
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    Quote Originally Posted by T 20 View Post
    That's about as far as I'm going to get today while I stare at the piston and think about the job, but I have a good idea which way this is going to go --- new piston.
    Well after looking at the Mercury piston for a while, measuring a few dimensions and calculating some weights I've decided that I'm definitely going to have to make a new piston --- again.

    There's some very weird designing went into the Mercury and Airsporter pistons which doesn't make much sense.
    The distance from the front of the piston cocking lever slot to the front of the piston head is 37mm --- on a HW95 this measurement is 17mm, the weight of this 37mm of piston head is about 90grams and would be difficult to shed any significant weight from.
    So it looks like it would be quicker and easier for me to machine a completely new lightweight piston body to screw the original BSA latch rod into rather than try to lighten the original Mercury piston.



    All the best Mick

  14. #29
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    T.P. Length

    On a Mk4 Airsporter it's 20mm long plus the loading tap so less efficient but it makes the power with a little love .

  15. #30
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    Cheers, crowbar.

    Good luck with the piston build, Mick. Obviously this is going to be more involved than first envisaged but will prove an interesting journey.
    THE BOINGER BASH AT QUIGLEY HOLLOW. MAKING GREAT MEMORIES SINCE 15th JUNE, 2013.
    NEXT EVENT :- May 17/18, 2025.........BOING!!

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