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  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 online now Killer Vampire Lesbians on scooters
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    The .177 will run much smoother at 10.5. Lose half a coil and try again, repeat if necessary.
    God rest ye jelly mental men

  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!!
    God rest ye jelly mental men

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