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Thread: Is it practical to recharge Gifford cylinders to fire them?

  1. #16
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    Giffard threads

    Thread sizes on the Giffard Co2 reservoirs are as follows:-
    Rifle 20mm x 2.0
    Pistol 16mm x 1.5

    And although the thread for the Co2 tank is an odd size, you can use 7/8” x 14 UNC which is as near as you can get.

    Hope this helps,

    Cheers Lawrie.

  2. #17
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    i have had to put a sleeve in between the valve and the spring retainer as the air was pushing the nylon and o-ring back up the tube against the spring rather than going thru the valve to fill it ,
    i put maybe 1000 psi in to try and got 330 fps with 45grain (around 11foot pounds )and after a few shots it dropped some - not much but its the sleeve i put in restricting the flow - that was with air but i think co2 might be similar in power but would be safer as i dont know what pressures the cylinder would stand - i did not dare put more than 1000psi in , i will leave it at that as i am pleased to be able to shoot it a little allthough i am wondering if i could sleeve the barrel to .177 (only if its totally reversible without damaging it at all )it could be a nice thing to use

  3. #18
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    A few years ago Martin Herrick, who's a brilliant gunsmith, found me a rusty old Giffard barrel in Poland. He skimmed the pitting off the outside of the barrel but managed to keep the gold lettering. He then sleeved it to .22. I unscrewed the 8mm barrel on my rifle ( very carefully but it's not difficult to do ) and now i have two barrels which i can swap over. The .22 is shooting at a very nice 10.5 ft/lb. Martin also adapted an old Mossberg peep sight for me so now i have a nice 'target' outfit. There are pictures of it on the vintageairgun site.

  4. #19
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    Quote Originally Posted by j_potter View Post
    A few years ago Martin Herrick, who's a brilliant gunsmith, found me a rusty old Giffard barrel in Poland. He skimmed the pitting off the outside of the barrel but managed to keep the gold lettering. He then sleeved it to .22. I unscrewed the 8mm barrel on my rifle ( very carefully but it's not difficult to do ) and now i have two barrels which i can swap over. The .22 is shooting at a very nice 10.5 ft/lb. Martin also adapted an old Mossberg peep sight for me so now i have a nice 'target' outfit. There are pictures of it on the vintageairgun site.

    I Just took a look at the site you mention your gun looks truly stunning in its repro box!

  5. #20
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    Is it known what the muzzle velocity for each of the Giffard rifle calibres was?

  6. #21
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    Quote Originally Posted by wild boar View Post
    i have had to put a sleeve in between the valve and the spring retainer as the air was pushing the nylon and o-ring back up the tube against the spring rather than going thru the valve to fill it ,
    i put maybe 1000 psi in to try and got 330 fps with 45grain (around 11foot pounds )and after a few shots it dropped some - not much but its the sleeve i put in restricting the flow - that was with air but i think co2 might be similar in power but would be safer as i dont know what pressures the cylinder would stand - i did not dare put more than 1000psi in , i will leave it at that as i am pleased to be able to shoot it a little allthough i am wondering if i could sleeve the barrel to .177 (only if its totally reversible without damaging it at all )it could be a nice thing to use
    You will not get many shots with 1000 psi of air, the power will drop off rapidly. CO2 is much better, giving many more shots at a fairly constant velocity especially in warm weather. With CO2 you have a dense liquid supply that is slowly vaporising to gas. With the air at 1000 psi it is constantly falling in pressure at every shot.

    Baz
    BE AN INDEPENDENT THINKER, DON'T FOLLOW THE CROWD

  7. #22
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    I've made up a couple of adaptors in the past for charging some antique cylinders (with mixed success), and I've been putting a little thought into the Giffards for a while. Just a quick query, can anyone confirm for me that the screw thread used on the modern 88 Gram Co2 containers and adaptors for 12 gram bulbs, is 16 mm x 1.5 . I've never used them so have nothing here to measure.

  8. #23
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    It's a while since this thread started and I've been doing some thinking and fiddling in my shed.
    I've turned a short adaptor from brass which holds a Co2 screw in bulb. I've kept it fairly simple and purposely made the valve a fair bit smaller than the original Giffard one, I'm more interested in seeing if it's feasible rather than producing lots of power.
    I haven't tried it with a projectile (other than a cotton bud poked in from the muzzle) yet, but it certainly releases a satisfactory sounding crack when the hammer falls. I've still got some work to do this afternoon with gaskets / O rings , those 16 gr. cylinders soon empty themselves if the seals are anything other than perfect. I know that some people are interested in similar projects and I will update when I've tied it properly.

  9. #24
    arnie2b Guest

  10. #25
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    Yes, thanks, the Buxton Air Conversion is very impressive and shows what can be done with these fantastic old rifles but I don't want to go down that route with all of the power implications. I'm keeping down to low power by restricting the size of my valve inside of the unit to a 1/4 inch dia. and the actual gas port to 1/16 th.

    Update.
    I've got it sealed nicely, but I think that in order to keep the power low, I've over complicated it a little by placing a small valve inside of the body which requires a second small diameter firing pin pushed by the original Giffard one, I machined it so that it only opens 20 thou and passes the gas through a secondary 1/16 th. inch dia. port. The good news is that it does seem to work, it makes a nice crack as the gas is released. I have no suitable lead balls at the moment so have turned some nylon 3/8 inch long pellets that are a nice fit in the bore and am muzzle loading them with a ramrod. They do travel 20 feet or so and I'm quite happy with that, I purposely made it without any adjustable parts but I will be able to strip it and turn a few more thou off the valve seating face to increase the flow when I have some means of testing it properly.
    Last edited by mel h; 18-02-2019 at 01:38 PM. Reason: update

  11. #26
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    update

    Since my last post here I've found a bit of time and opened the small port in my adaptor in order to let a little more co2 pass through, I've now found that modern plastic 6mm airsoft balls are a good fit and with the fairly low power that I'm achieving they make nice holes in paper targets, the perfect antique plinker.

    I took a couple of photo's but I don't seem to be able to attach them.
    Last edited by mel h; 08-03-2019 at 01:07 AM.

  12. #27
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    Reseal

    Quote Originally Posted by Lawrie Amatruda View Post
    I have resealed many Giffards over the years, if you have the right tool to disassemble them they are simple to do, just one seal needed, I have never come across one that looked unsafe to use, for example being rusty on the inside.

    Regards, Lawrie.
    What are you using to replace the seal?

    Jabberwalky

  13. #28
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    Quote Originally Posted by jabberwalky View Post
    What are you using to replace the seal?

    Jabberwalky
    I use 95 hardness cast polyurethane rod, only one seal needed, a very efficient and simple valve system.

    Cheers, Lawrie.

  14. #29
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    Quote Originally Posted by Lawrie Amatruda View Post
    I use 95 hardness cast polyurethane rod, only one seal needed, a very efficient and simple valve system.

    Cheers, Lawrie.
    Lawrie I sent you an email the other day. Did you get a chance to read it please?
    Vintage Airguns Gallery
    ..Above link posted with permission from Gareth W-B
    In British slang an anorak is a person who has a very strong interest in niche subjects.

  15. #30
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    Em-Ge repeating air rifle magazine

    Quote Originally Posted by Garvin View Post
    Lawrie I sent you an email the other day. Did you get a chance to read it please?
    Hi Danny,

    Sorry about not replying, you sent the email to my old address which is not used very often, anyway I have now seen it, I’m not sure what measurements you require, but it is a quite complicated magazine, I am not an engineer and would only be able to give basic external measurements, the one I have is a copy of one belonging to Vic Turner of Protek, made for me by an engineer quite a few years ago, so not sure if the measurements I could give would be of use, it is larger than the pistol magazine measurements, the pictures on your vintage site don’t show the complicated machining necessary to make it. If I can help I am quite happy to do so. I had two of the pistols, both had repro. magazines, I sold one a couple of years ago.

    Kind regards,

    Lawrie
    Last edited by Lawrie Amatruda; 18-10-2023 at 10:53 PM.

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