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Thread: Softer HW99 Mainspring?

  1. #1
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    Softer HW99 Mainspring?

    My 0.177 HW99 has had the usual fettling including a Delrin top hat, spring guide and a PTFE piston sleeve. It currently has the standard HW mainspring without preload washers, and shoots JSB 8.5 gn. at 11.25 Ft.Lbs.

    I would like to trade some power for a smoother firing cycle, thinking that an alternative, softer mainspring would be a better solution than cutting a coil or so off the existing mainspring.

    Is fitting a softer mainspring the best approach, and if so could someone suggest an alternative mainspring?

    Thanks and Best Regards,
    Bill.

  2. #2
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    Quote Originally Posted by billsnibby View Post
    My 0.177 HW99 has had the usual fettling including a Delrin top hat, spring guide and a PTFE piston sleeve. It currently has the standard HW mainspring without preload washers, and shoots JSB 8.5 gn. at 11.25 Ft.Lbs.

    I would like to trade some power for a smoother firing cycle, thinking that an alternative, softer mainspring would be a better solution than cutting a coil or so off the existing mainspring.

    Is fitting a softer mainspring the best approach, and if so could someone suggest an alternative mainspring?

    Thanks and Best Regards,
    Bill.
    I have a wonky donkey service kit in my 99s and that came with a longer spring in the kit

  3. #3
    tinbum's Avatar
    tinbum is offline Friend of Dorothy's friend's tennis partner
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    The .177 will run much smoother at 10.5. Lose half a coil and try again, repeat if necessary.
    Disclaimer: The above is merely an opinion and usually wrong. It should be taken with caution and not as fact. Any insult to any person, group, race or species is probably unintentional unless expressly directed. Contents may settle during transit. Always read the label!

  4. #4
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    As the man says above, just shortening the existing spring slightly may well have the desired effect.

    I have a WonkyDonky kit in one of my 99s and it's lovely. You could approach him and see if he has a spring. I could well be tempted to ask him for a .22 spring, sacrificing power for the even milder cycle that you are after, although some would say that it may drop the power too low. Worth a try in my opinion and you could add a little preload if the output was too low.

    If you have the spring out of the gun at present, you could check its measurements against some of those stated on the Mainspring Data Thread in the Useful Tips section.

    If choosing a new spring, don't forget you'll need to make sure that the guide (and top hat if desired) fit properly.
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  5. #5
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    Thanks all for the advice. A thought: would collapsing a coil have the smoothing effect on shooting characteristics I'm after?

    It seems that this would be the equivalent of shortening the spring and adding some preload washers, and wouldn't involve having to refinish the spring end. If it wasn't beneficial I could then remove the collapsed coil and refinish the end to achieve the shortened spring situation.

    Best Regards,
    Bill.

  6. #6
    tinbum's Avatar
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    Quote Originally Posted by billsnibby View Post
    Thanks all for the advice. A thought: would collapsing a coil have the smoothing effect on shooting characteristics I'm after?

    It seems that this would be the equivalent of shortening the spring and adding some preload washers, and wouldn't involve having to refinish the spring end. If it wasn't beneficial I could then remove the collapsed coil and refinish the end to achieve the shortened spring situation.

    Best Regards,
    Bill.
    It will work, but added dead preload often increases cocking effort and piston bounce for the same power.
    However, it is quick, easy and FREE!!
    Disclaimer: The above is merely an opinion and usually wrong. It should be taken with caution and not as fact. Any insult to any person, group, race or species is probably unintentional unless expressly directed. Contents may settle during transit. Always read the label!

  7. #7
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    I run mine with a longer, softer spring. Nicer, softer firing cycle, easier cocking, and less piston bounce.. power is actually unchanged at just over 11 (in .177)
    I'm currently looking for: an old style Parker Hale (not Pax) Phoenix, a .177 mk1 Meteor barrel ( or a whole gun if cheap), and a project Crosman 2200 (or bits). Thanks, JB.

  8. #8
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    Quote Originally Posted by Shed tuner View Post
    I run mine with a longer, softer spring. Nicer, softer firing cycle, easier cocking, and less piston bounce.. power is actually unchanged at just over 11 (in .177)
    Excellent, but do you know which rifle that spring was original equipt for?
    Cheers, Phil

  9. #9
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    I remember talking to Shauny about this and he finds a Titan meteor spring (cant remember the number), works well in these. Probably need a piston sleeve as likely be of smaller diameter.

  10. #10
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    Quote Originally Posted by Phil Russell View Post
    Excellent, but do you know which rifle that spring was original equipt for?
    Cheers, Phil
    err, well.... it was the 4th one I found in the second drawer of my cantilever toolbox full of springs...
    I'm currently looking for: an old style Parker Hale (not Pax) Phoenix, a .177 mk1 Meteor barrel ( or a whole gun if cheap), and a project Crosman 2200 (or bits). Thanks, JB.

  11. #11
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    Ah yes I know that spring

  12. #12
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    Quote Originally Posted by Shed tuner View Post
    err, well.... it was the 4th one I found in the second drawer of my cantilever toolbox full of springs...
    Now there is a man after my own heart ......
    Cheers, Phil

  13. #13
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    Bill,

    I fitted a 0.22" Wonky Donky service kit into my 0.177" HW99S, and it made ca. 10.0 ft.lb, with no compression washers fitted.

    Lovely to shoot, and much easier to cock that when the rifle is at ca. 11 ft.lb.

    Compare the trajectories of 10 ft.lb, and 11.5 ft.lb in Chairgun, and you see you are losing virtually no trajectory with 10 ft.lb

    Have fun

    Best regards

    Russ

  14. #14
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    Shortening a spring increases stiffness so not the ideal way to go. If Konceptus starts trading again their springs are very nice - softer than standard. My Konceptus kitted 99 is excellent.

    For a meteor spring use an early mark of meteor and original equipment...

  15. #15
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    Titan meteor spring is no. 5. I have used these in some guns but wouldn't say they were particularly soft. The spring in my HW50 is an old one out of my 22 95. Produces 11 in 22. TX mk3 springs are quite weedy so may be worth a look to see if they would fit.
    Plinkerer and Tinkerer

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