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  1. #1
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    working out FT LBS TO FPS

    hi there

    im looking for information
    how to convert
    780fps to ft lbs
    or a 1000fps

    ive found nothing to help
    so im wondering if anyone here can

    thanks

  2. #2
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    http://extorian.co.uk/shooting/pellets.html

    depends on pellet weight

    8.4 grain@ 780 fps= 11.35lbft
    8.4 grain @ 1000 fps=18.66lbft
    aa s409k .177, cs700 stock, mtc mamba 4-16x50, logun qgs

  3. #3
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    converting ftlb to fps

    Quote Originally Posted by tye8180 View Post
    http://extorian.co.uk/shooting/pellets.html

    depends on pellet weight

    8.4 grain@ 780 fps= 11.35lbft
    8.4 grain @ 1000 fps=18.66lbft
    that cant be right as i put my rim fire on the crono and it fired at 980 fps that would mean it was fireing under 18ftlb nar cant be should be around 900ftlb?? have another look at that matie

  4. #4
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    Quote Originally Posted by mal mason View Post
    have another look at that matie
    After nearly 4 years he's probably beyond caring.

  5. #5
    Big Dave is offline Formerly known as Badger410
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    Quote Originally Posted by mal mason View Post
    that cant be right as i put my rim fire on the crono and it fired at 980 fps that would mean it was fireing under 18ftlb nar cant be should be around 900ftlb?? have another look at that matie
    I think you need to look at the equation again.

  6. #6
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    Quote Originally Posted by mal mason View Post
    that cant be right as i put my rim fire on the crono and it fired at 980 fps that would mean it was fireing under 18ftlb nar cant be should be around 900ftlb?? have another look at that matie

    Check your figures again. 1000ft/lb rimmie? Firing an 8 grain bullet?

  7. #7
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    Quote Originally Posted by mal mason View Post
    that cant be right as i put my rim fire on the crono and it fired at 980 fps that would mean it was fireing under 18ftlb nar cant be should be around 900ftlb?? have another look at that matie
    no it wouldnt as your rim fire round would be weighing at 40grns as that is the average weight for sub sonic. therefore your rimfire running at 980 is knocking out about 85ftlb which is correct. hence if you were using high velocity rounds they weigh a lot less usually around the 32 grn weight the velocity comparable will be a lot higher.

    980x980x40 divided by 450240 =85.32ftlb.

  8. #8
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    thought they had 3 power ratings that you could switch between,
    aa s409k .177, cs700 stock, mtc mamba 4-16x50, logun qgs

  9. #9
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    true mate

    but to err is human my friend
    Rapid 7 / 10-22 ATN 2 Stiller Predator .204 Pulsar N970 Tikka T3 semi custom ATN MARS thermal.204 Tikka T3 Semi.223 Wylde IOR Operator Lawton 6mmBR Kahles Gen 3 - Stiller 6.5 x 47 Bushnell BDX - Winchester Red Performance SX3 12g

  10. #10
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    Quote Originally Posted by a88ott View Post
    hi there

    im looking for information
    how to convert
    780fps to ft lbs
    or a 1000fps

    ive found nothing to help
    so im wondering if anyone here can

    thanks
    You need to know the weight of the pellet in grains (some tins do have the weight written on them).

    Say you are using a pellet that weighs 7.5gns.

    The formula is:

    Muzzle velocity squared, multiplied by the weight of the pellet, divided by 450240.

    The result is in ft/lbs.

    780x780=608400
    608400x7.5=4563000
    4563000/450240= 10.13ft/lbs.


    This is a formula that I have used since the 70's so there may be an easier or better method of working it out and if this is the case I'm sure that someone will come along and correct me.
    I hope this is of assistance.

    Regards,
    Gary.

  11. #11
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    Spot on...

    Quote Originally Posted by gtfreight View Post
    You need to know the weight of the pellet in grains (some tins do have the weight written on them).

    Say you are using a pellet that weighs 7.5gns.

    The formula is:

    Muzzle velocity squared, multiplied by the weight of the pellet, divided by 450240.

    The result is in ft/lbs.

    780x780=608400
    608400x7.5=4563000
    4563000/450240= 10.13ft/lbs.


    This is a formula that I have used since the 70's so there may be an easier or better method of working it out and if this is the case I'm sure that someone will come along and correct me.
    I hope this is of assistance.

    Regards,
    Gary.
    Stick with this formula!

    Tony
    If you wade in, you have to risk the water coming over the tops of your wellies...

  12. #12
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    I think what the man is after is, the theoretical maximum muzzle velocity of a 12 ft/lbs air rifle, depending upon the weight of the pellet being used. At the end of This Link, is an image of the usual formula re-arranged to make Muzzle Velocity (in feet per second) the subject. You'll need a calculator with a square root key - use Windows' own calculator. Regards ... Geek
    PauL H. - Shotgoon
    Brownings: 1999 Ultra XS; 2004 B525 Field; 2010 Maxus Hunter: Air Arms 1998 Mk.2 Pro-Target, 2001 Mk.2 Pro-Sport & 2003 S400C

  13. #13
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    ok thanks

    but how do i find the Muzzle velocity
    on a air rifle ?

    thanks

  14. #14
    alan-aitch. is offline Burris Burris Burris Burris Burris Burris
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    Try this......

    Click

    You can edit the pellet list to add your pellet and weight, (look in the help file) then you can input the required ftlb and it will tell you the fps for the selected pellet, or you can input the fps and it'll tell you the power.

    Alan.

  15. #15
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    Quote Originally Posted by a88ott View Post
    ok thanks

    but how do i find the Muzzle velocity
    on a air rifle ?

    thanks
    Use a Chronoscope, though some people call these devices Chronographs. Regards ... Geek
    PauL H. - Shotgoon
    Brownings: 1999 Ultra XS; 2004 B525 Field; 2010 Maxus Hunter: Air Arms 1998 Mk.2 Pro-Target, 2001 Mk.2 Pro-Sport & 2003 S400C

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