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Discussion in 'Shooting Related Threads' started by E. Beaver, Jan 12, 2010.

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  1. E. Beaver

    E. Beaver Member

    Oct 27, 2007

    My used BT99 Plus has a system that is a two-stage affair, with the first stage on the light side and then about half way through the second stage starts and it is much stiffer. It clunked when compressed. The first stage was so light that sometimes just as I was going to shoot it would compress a bit and mess up my shot.

    Took it apart, cleaned it up, oiled it and noticed that if I advance the innermost “plug” a little I could get rid of the clunk but this shortened the overall travel and upped the stiffness a little. Using a bathroom scale the maximum compressive force was 45 pounds.

    A rebuilt recoil unit was purchased tecently wherein the plunger holding the innermost spring was removed and replaced with a second smaller spring that fit inside the innermost spring. Removing the plunger deactivated the heavier outermost spring leaving the total recoil determined by the original forward spring and the new smaller spring. The maximum compressive force of this set-up was 35 pounds. I liked the feel of the now single stage compression as it was smooth and continuous but it was too light for my use.

    Went to the local Ace Hardware store and picked up some likely springs.
    The heavier spring was 2.25” long, .715” OD, .090” wire and 11 coils and an approximate value of 40 pounds/inch. A lighter spring was 2.0” long, .428” OD, .054” wire and 15 coils and an approximate value of 15 pounds/inch. I ground the ends of the heavier spring to shorter it about 1/8” so it would permit full travel under compression.

    With the heavier spring installed in the forward position it gave a maximum compressive force of 50 pounds. With both springs installed the max force was 60 pounds. The maximum travel was a little over 3/8”. Springs vary so your values might be different. I shot 50 Remington Nitro 27 (1235 fps) with both springs in place and really appreciated the smoothness, no noise and the recoil reduction. I’ll try it with just he heavier spring next time.

    This is a fairly straightforward changeover and the whole system can be changed back to the original without any permanent change to the gun. Below are step-by-step instructions and use them at your own risk.

    1.Loosen the setscrew several turns in the recoil plate.

    2.Unscrew the recoil pad and pad plate.

    3.Remove the two screws holding the stock plate.

    4.Remove the two screws holding the reducer assembly.

    5.Remove the assembly from the stock.

    6.There is no need at this time to remove the plug from either end of the assembly.

    7.Clamp the assembly lengthwise in a large vice or use a “Pony” clamp etc and compress the unit about ¼”. This removes any strain on the small screws holding the assembly together.

    8.Remove the two small screws located in the slots of the assembly.

    9.Carefully release the clamp and separate the assembly.

    10.Remove the spring and plunger from the forward part of the assembly.
    Nothing needs to be done to the rearward part of the assembly.

    11.Clean the mating parts and check for free movement, polish if necessary.

    12.For approximately 50 pounds of compression use only the heavier spring.
    For approximately 60 pounds of compression use both the heavier and lighter springs.

    13.Position the whole assembly in the clamp and compress until the threaded end where the pad plate is attached is almost contacted. If you are more than about 1/16” away from the threads you will need to shorten the springs.

    14.When grinding the ends of the springs dip them in water frequently to keep from overheating and changing the temper.

    15.Check the compression force and free movement using a bathroom scale etc.

    16.If you have installed both springs you have the option of using the forward plug to adjust the tension of the smaller spring. Double check that you have full travel.

    17.Reassemble in the reverse order.

    This turns your recoil system into a smooth single stage system. Good luck and good shooting.

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