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Thread: Bam B50 / B51 power mods

  1. #1
    ice's Avatar ice
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    Default Bam B50 / B51 power mods

    Hi all, been "playing" with Bam50 to get best consistency for hunting.

    The best i could manage was 50 shots @ 20 ft/lbs with 10.6gr H&N's with an E.S of 33fps, which i believe is acceptable for hunting. I use a fill pressure of 170bar and after 50 shots it dropped to 115bar.

    This was done by adjusting the lenght of the striker and thus lowering the standard velocity by about 60fps.

    Did any of you manage to get better/more consistent shots per fill?

    Have any of you tried a weaker striker spring?

    Transfer port mods? - not 12ft/lbs.

    Thanks.
    <span class='smallblacktext'>[ Edited ]</span>
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  2. #2
    Marksman
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    Ice that is already outstanding for the BAM!!
    I doubt very much you will get better than an ES of 33fps at 20ft\lbs over 50 shots...even that is difficult to believe after my experience with the BAM with a standard striker and spring.
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  3. #3
    ice's Avatar ice
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    I've tried several adjustments/ fill pressures and that was the best. Did the chrony test twice, with same results.

    905.4
    923.8
    926.1
    929.6
    926.7
    930.3
    930.3
    932.3
    933.3
    930.9
    931.0
    931.8
    928.4
    923.8
    927.9
    922.4
    917.9
    921.2
    914.1
    911.2
    909.4
    906.3
    902.2
    902.3
    915.5
    915.2
    910.8
    911.5
    911.2
    905.7
    906.4
    904.2
    902.2
    901.3
    901.7
    900.3
    904.5
    904.8
    901.5
    909.4
    904.2
    908.4
    905.0
    908.8
    911.9
    912.7
    911.3
    911.2
    914.1
    915.1

    What was your experience?
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  4. #4
    Marksman
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    you must have a really good BAM.

    I have had 2 and at that power level the power simply drops after every shot from 1000fps down to 800fps in the space of 50 shots.
    Yours must be a newer one with a smaller transfer port and\or a different striker setup
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  5. #5
    Protea FT Team '08

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    Well Ice it looks good to me.50 shots at that power level is quite good I think.
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  6. #6
    ice's Avatar ice
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    Some of the guys from the yellow forum claims 12fps e.s, so there is some very consistent bam's out there.

    Cheers.
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  7. #7
    MOT: Thomson Pneumatic Rifles

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    Hi Ice, see you private messages.
    Nice hunting set up, 33fps spread at the higher velocities will not effect hunting accuracy. As you go to the lower end 800fps and below the 30fps is a big drop.
    The rifle giving 12fps extreme spread is usuall for a short velocity string and more than likely from a tuned rifle.
    Here are some interesting stats on a bam:

    Out the box 8.4gns pellets 1070 to 921fps over 40 shots, still usable "hunting" accuracy despite the 150fps drop.

    Same rifle 10 shots with 10.5gn pellets, 10 shots 1005 to 940fps, air consumed 45bar

    Power port mod 10 shots 1025 to 990fps, air consumed 25bar.
    Efficiency improved by 45%. tune rifle back to +-1000fps and you will improve your shot count by +-40% while decreasing overall spread.

    Bam tuned at 790fps gives 60 shots and 23fps extream spread, but more interestingly arround 5fps from shot to shot!

    Bams are great "base rifles" for tuning given thier low price and high performance.
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  8. #8
    Protea FT Team '15
    REP: Daystate/Brocock Accredited Technician

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    Hi All

    I ply with the BAM a little and found the following: Change the transfer port, not really inpact of changing the striker length.
    Feet/s Ft/lbs Grain
    762.23 13.54 10.5
    758.54 13.4 10.5
    755.62 13.29 10.5
    744.86 12.91 10.5
    744.86 12.91 10.5
    744.15 12.91 10.5
    744.86 12.91 10.5
    741.34 12.81 10.5
    747.7 13.01 10.5
    749.12 13.08 10.5
    736.46 12.63 10.5
    745.56 12.94 10.5
    741.34 12.81 10.5
    734.39 12.56 10.5
    740.64 12.77 10.5
    739.94 12.74 10.5
    730.29 12.43 10.5
    727.58 12.33 10.5
    733.71 12.53 10.5
    728.93 12.36 10.5
    733.02 12.53 10.5
    719.57 12.06 10.5
    731.65 12.46 10.5
    723.55 12.19 10.5
    728.93 12.36 10.5
    715.63 11.92 10.5
    717.6 11.99 10.5
    709.8 11.72 10.5
    716.29 11.96 10.5
    718.25 12.02 10.5
    711.74 11.79 10.5
    707.24 11.66 10.5
    711.74 11.79 10.5
    708.52 11.69 10.5
    698.43 11.36 10.5
    703.44 11.53 10.5
    701.55 11.46 10.5
    696.57 11.3 10.5
    695.33 11.26 10.5
    697.81 11.33 10.5
    697.81 11.33 10.5
    698.43 11.36 10.5
    693.49 11.2 10.5
    692.26 11.17 10.5
    685.01 10.94 10.5
    692.87 11.17 10.5
    692.26 11.17 10.5
    686.81 10.97 10.5
    688.62 11.04 10.5
    680.25 10.78 10.5
    677.9 10.69 10.5
    679.08 10.75 10.5
    676.15 10.66 10.5
    681.44 10.82 10.5
    679.66 10.75 10.5
    675.57 10.63 10.5
    677.32 10.69 10.5
    667.52 10.38 10.5
    665.25 10.31 10.5
    670.37 10.47 10.5
    666.95 10.34 10.5
    666.38 10.34 10.5
    662.44 10.22 10.5
    663.56 10.25 10.5
    666.38 10.34 10.5
    659.66 10.13 10.5
    658 10.07 10.5
    657.45 10.07 10.5
    655.25 10.01 10.5
    650.9 9.85 10.5
    650.36 9.85 10.5
    650.36 9.85 10.5
    649.28 9.82 10.5
    646.61 9.73 10.5
    641.84 9.58 10.5
    640.79 9.55 10.5
    637.67 9.46 10.5
    627.47 9.17 10.5
    630.49 9.26 10.5
    634.06 9.37 10.5
    631 9.29 10.5
    626.46 9.14 10.5
    625.96 9.11 10.5
    623.48 9.05 10.5
    621.99 8.99 10.5

    If standard the following:
    Feet/s ft/lbs grain
    1034.74 20.04 8.44
    1030.66 19.89 8.44
    1027.96 19.77 8.44
    1023.93 19.62 8.44
    1021.27 19.54 8.44
    1017.29 19.39 8.44
    1021.27 19.54 8.44
    1012.04 19.2 8.44
    1009.44 19.08 8.44
    1005.56 18.93 8.44
    1004.27 18.9 8.44
    999.15 18.71 8.44
    997.88 18.63 8.44
    991.57 18.41 8.44
    991.57 18.41 8.44
    985.34 18.19 8.44
    982.87 18.08 8.44
    982.87 18.08 8.44
    977.97 17.89 8.44
    974.33 17.78 8.44
    973.12 17.75 8.44
    968.31 17.57 8.44
    964.74 17.42 8.44
    964.74 17.42 8.44
    956.5 17.13 8.44
    953.02 17.02 8.44
    949.56 16.88 8.44
    946.12 16.78 8.44
    942.71 16.63 8.44
    937.08 16.46 8.44

    Hope this help somebody.

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  9. #9
    Marksman
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    yeah...when I first tried the BAM I also got a totally unuseable power curve like the one above.

    only cure for me was to make a much smaller transfer port and turn in the striker adjustment for less travel

    ICE I have no idea how you achieved that consistency with a BAM out of the box.
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  10. #10
    ice's Avatar ice
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    Mine was doing 950 with 10.6gr (according to my F1 chrony). Bought the gun secondhand - dunno what was done by previous owner. Gun has been worked on as there was marks on the screws.

    I've cut a small groove in back of adjustable piece of the striker and removed the safety, this enabled me to do adjustments through the safety hole with a long, small screw driver without taking the gun apart everytime.

    Thanks alot to Warrick, Wyan.

    Guido, what are you implying with remarks like " hard to believe"?????.... :dunno did one of the roundhouse kicks backfired ?
    :jester
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  11. #11
    Marksman
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    I am implying that it is hard to believe that a BAM out of the box has that consistency...yours was obviously sorted by someone else.
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  12. #12
    Protea FT Team '15
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    I change my striker screw with a little grub screw , I can change the striker lentgh with a normal allen key from the back if I remove the saftey catch. I use two differnet lentgh of screws to determine what the impact is if you change the striker distance without any reel change at all. I change the transfer ports, the smaller one end up to be around 1,4mm opening, this was the only way I can tame the rifle to become 12ft/lbs or in that range.
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  13. #13
    Marksman
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    exactly what I did to my ex BAM...
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  14. #14
    ice's Avatar ice
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    Hi Wyan, with the current setting my gun is doing low 600 if i fill it to 180/190 bar. From 165/170 bar, it's spot on. At 175bar it shoots at 820 - 840fps with 10.6gr Baracuda pellets.

    What is the standard transfer port size?

    The gun is very accurate with heavy pellets, but maybe i must convert it to sub 12ft/lbs and kick some LG 110 a$$ at the next ft shoot!

    Thanks for the info.
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  15. #15
    SAFTAA Chairman
    Protea FT Team '12/'16/'17
    MOT: Steyr Sport Service South Africa

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    i have had my bam tuned down to sub 12ft/lbs
    i would be great to have another bam shooting with me
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