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Thread: I don't believe a TP smaller than 3.0mm ever works in a 12FP springer....

  1. #46
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    Quote Originally Posted by Rich View Post
    I think a taper reamer is a better way to go than a twist drill; it would be remarkable if a twist drill was that accurate, as any imperfection in the grind will make it cut oversize.
    yup, I have a taper reamer that goes from 2.5-3.5 perfect range. I also have a couple of 3.0 and 3.2 parallel reamers, as it's amazing how often that's where the sweet spot ends up (even allowing for the variation in port length, calibre, piston weight, preload, piston mass, and the phases of the moon )
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

  2. #47
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    Quote Originally Posted by les allam View Post
    I think the 80 has a 2.8mm TP standard from the factory, two of mine do.
    Les..
    My Webley Xocet has a 2.6mm transfer port and produces power easily...
    .22 S410...
    .22 Webley Xocet...
    .22 HW95k...

  3. #48
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    Quote Originally Posted by TORNADOS7 View Post
    My Webley Xocet has a 2.6mm transfer port and produces power easily...
    I bet if you opened it up to 3.0 it would produce power more easily / more efficiently / with less recoil and cocking effort
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

  4. #49
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    I am following this topic with interest as there is much excellent information here. I well remember the debate over the LGU TP and how it was best to open it out to 3.2mm for a better performance and, if I remember correctly, to avoid stress on the factory fitted mainsprings.
    But I digress. In reading these posts, someone could be forgiven for thinking that manufacturers have got it all wrong ... usually using TPs that are too narrow or, in some cases, too wide for peak efficiency. I have been pondering why this is ... There are several explanations amongst which is the possibility that the manufacturer chooses a TP size without any real research into its performance; a case of 'oh, that'll do'. Or the chosen size may be a production based compromise to use one size for different markets rather than matching a size to a particular market. Did not Walther do that with the LGU with the TP for the USA market being larger than that for Germany (and the UK)? Or maybe the manufacturer tries to provide a solution by using a TP restrictor (K98?).

    Thank heaven for people like those on here who do the hard work for us.

    Cheers, Phil

  5. #50
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    Quote Originally Posted by Phil Russell View Post
    I am following this topic with interest as there is much excellent information here. I well remember the debate over the LGU TP and how it was best to open it out to 3.2mm for a better performance and, if I remember correctly, to avoid stress on the factory fitted mainsprings.
    But I digress. In reading these posts, someone could be forgiven for thinking that manufacturers have got it all wrong ... usually using TPs that are too narrow or, in some cases, too wide for peak efficiency. I have been pondering why this is ... There are several explanations amongst which is the possibility that the manufacturer chooses a TP size without any real research into its performance; a case of 'oh, that'll do'. Or the chosen size may be a production based compromise to use one size for different markets rather than matching a size to a particular market. Did not Walther do that with the LGU with the TP for the USA market being larger than that for Germany (and the UK)? Or maybe the manufacturer tries to provide a solution by using a TP restrictor (K98?).

    Thank heaven for people like those on here who do the hard work for us.

    Cheers, Phil
    Quick and easy way to restrict power for their none core markets .

  6. #51
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    Quote Originally Posted by Shed tuner View Post
    I bet if you opened it up to 3.0 it would produce power more easily / more efficiently / with less recoil and cocking effort
    Had considered it buddy, biggest change in shot cycle has been removing weight from the piston, standard it's 273grms, currently 255, looking to reduce a little more yet though...

    I hadn't shot it for a while since the weight reduction but picked it up the other day and all the kick that I'd come to expect has all but disappeared...

    Shoots/feels better than my .22/95k now...
    .22 S410...
    .22 Webley Xocet...
    .22 HW95k...

  7. #52
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    Quote Originally Posted by TORNADOS7 View Post
    Had considered it buddy, biggest change in shot cycle has been removing weight from the piston, standard it's 273grms, currently 255, looking to reduce a little more yet though...

    I hadn't shot it for a while since the weight reduction but picked it up the other day and all the kick that I'd come to expect has all but disappeared...

    Shoots/feels better than my .22/95k now...
    255g is a good improvement - what are these 27 or 28mm cylinder ?
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

  8. #53
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    Quote Originally Posted by Shed tuner View Post
    255g is a good improvement - what are these 27 or 28mm cylinder ?
    27mm buddy, looking to get the piston down to around 240, the spring is the main issue with these really (Pow-R-Lok F1) as they were well oversprung from the factory...
    Last edited by TORNADOS7; 02-08-2021 at 04:23 PM.
    .22 S410...
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    .22 HW95k...

  9. #54
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    I've had great results with only a softer spring in the Vulcan. The heavy piston and the narrow transfer port seem to balance out nicely.
    Too many airguns!

  10. #55
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    Thumbs up

    Quote Originally Posted by evert View Post
    I've had great results with only a softer spring in the Vulcan. The heavy piston and the narrow transfer port seem to balance out nicely.
    The shot cycle on the Xocet is quite horrific as standard but as I said I seem to be getting good results just by removing weight from the piston, 273grms is heavy, I’ve also been able to reduced preload as a result, currently running pretty much smack bang on 11, hoping to lose a bit more off of the piston yet whilst maintaining 11’s…
    .22 S410...
    .22 Webley Xocet...
    .22 HW95k...

  11. #56
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    Being around in the 80's we drilled them...no chronos just the "thats better through the bit of wood" scientific approach.
    I think we did see improvements up to a point but I really don't recommend this type of Tinkering.

    Leave them alone or try to limit it to 3.5mm unless you can make plugs and revert if required.

    I can't deny its addictive to tinker with springers though.
    Ed - HW77 mk2 .22 + Vmach kit - HW80 mk1 .25 + Vmach kit - Webley Tempest 1979 -
    https://www.harrisontelescopes.co.uk

  12. #57
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    Quote Originally Posted by accused View Post
    Leave them alone unless you can make plugs and revert if required.
    The very reason I haven't touched the Xocets transfer port buddy...
    .22 S410...
    .22 Webley Xocet...
    .22 HW95k...

  13. #58
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    Quote Originally Posted by Shed tuner View Post
    'cos that'll be too big
    Interestingly the old pre-wat BSA underlevers were made like this, as the loading tap was reamed through. They benefit massively from being sleaved down to 3mm or so - more power, less harsh..

    Another practical reason is to stop your pellets falling back into the cylinder through them
    Quote Originally Posted by Rich View Post
    Any void space has to be filled with the air that the piston is compressing, so a port larger than necessary will also reduce the maximum potential pressure.

    A while back I made a number of screw-in ports for a chap who was experimenting with a Walther rifle. The screw-in ports started out as brass grub screws that would screw into a tapped 'port', and they were all primarily drilled 2.0mm. Then with a taper reamer I opened them out, one by one, from 2.1mm in 0.1mm increments up to 3.0mm which was the largest he wanted. I reamed them back to front, if you follow me, so that the hole in the port diverged marginally, as this ought to give a better flow characteristic than a port that got smaller.

    I made the taper reamer from silver steel and the taper was chosen so that I could easily judge the bore size by the depth the reamer had entered.

    I think a taper reamer is a better way to go than a twist drill; it would be remarkable if a twist drill was that accurate, as any imperfection in the grind will make it cut oversize.
    Thanks both, dimly beginning to understand now.

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