Pennsylvania Firearm Owners Association
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  1. #1
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    Default 55gr vs 77gr Data

    Does anyone have bullet path/drop data they are able to share for a 1 in 7 twist, 16" AR for M193, and Mk262 (and M855 would be awesome too)? Say out to 400-600 yds.

    I'm having trouble finding this data on the web so if anyone has recorded data using good statistical analysis that would be awesome. I would do it myself but I'm limited without money to spend on Mk262, a good bench rest, and a range >100yds. But I do have good MS Excel skills .

    My goal is to be able to dope a rifle to the different loads to a decent degree of accuracy without physically shooting a statistically significant number of rounds.

    A chart would be great but the raw data would be excellent too. Perhaps if we collect more than one data set, I can average that and do some stats to provide to everyone interested in a nice format.

  2. #2
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    Default Re: 55gr vs 77gr Data

    Speer reloading manuals list ballistic tables out to 500 yds you'll need to know the BC and muzzle vel for the loads out of the shorter 16 " barrel . An example :

    55 gr fmj with BC of .250 and MV of 3100fps, sight above bore 1.5" ,rifle zeroed at 100 yd

    200yd drop 3.3"

    300 yd drop 12.8"

    400 yd drop 30.9"

    500 yd drop 60.7"
    Last edited by Tim Ault; September 11th, 2017 at 11:29 AM.

  3. #3
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    Default Re: 55gr vs 77gr Data

    Quote Originally Posted by Tim Ault View Post
    Speer reloading manuals list ballistic tables out to 500 yds you'll need to know the BC and muzzle vel for the loads out of the shorter 16 " barrel . An example :

    55 gr fmj with BC of .250 and MV of 3100fps, sight above bore 1.5" ,rifle zeroed at 100 yd

    200yd drop 3.3"

    300 yd drop 12.8"

    400 yd drop 30.9"

    500 yd drop 60.7"
    Thanks Tim. In that case I'd expand my question out to: Does anyone have velocity averages for the above loads out of a 16" barrel and the Speer tables to post or use to calculate the trajectories?

  4. #4
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    Default Re: 55gr vs 77gr Data

    Take a look at forums based on the AR-15. If the answer isn't found, sign up and ask. Looking for tables based on length of barrel is really looking for tables based on muzzle velocity. People on the forums who chronograph their loads will help folks with questions.

  5. #5
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    Default Re: 55gr vs 77gr Data

    Found this velocity data for different loads and barrel lengths. This combined with Federals online ballistics calculator has me setup.


    MK 262 VELOCITY DATA

    __________________________________

    7.5" 2053 FPS ... 10.5" 2363 FPS

    DIFFERENCE 310 FPS

    DIFFERENCE/INCH 103 FPS

    10.5" 2363 FPS ... 14.5" 2576 FPS

    DIFFERENCE 213 FPS

    DIFFERENCE/INCH 53 FPS

    14.5" 2576 FPS ... 16" 2669 FPS

    DIFFERENCE 93 FPS

    DIFFERENCE/INCH 62 FPS

    16" 2669 FPS ... 18" 2769 FPS

    DIFFERENCE 100 FPS

    DIFFERENCE/INCH 50 FPS

    18" 2769 FPS ... 20" 2818 FPS

    DIFFERENCE 49 FPS

    DIFFERENCE/INCH 25 FPS

    M855 VELOCITY DATA

    __________________________

    7.5" 2244 FPS ... 10.5" 2639 FPS

    DIFFERENCE 395 FPS

    DIFFERENCE/INCH 132 FPS

    10.5" 2639 FPS ... 14.5" 2861 FPS

    DIFFERENCE 222 FPS

    DIFFERENCE/INCH 56 FPS

    14.5" 2861 FPS ... 16" 2938 FPS

    DIFFERENCE 77 FPS

    DIFFERENCE/INCH 51 FPS

    16" 2938 FPS ... 18" 3046 FPS

    DIFFERENCE 108 FPS

    DIFFERENCE/INCH 54 FPS

    18" 3046 FPS ... 20" 3061 FPS

    DIFFERENCE 15 FPS

    DIFFERENCE/INCH 7.5 FPS

    XM193 VELOCITY DATA

    _________________________________

    7.5" 2364 FPS ... 10.5" 2755 FPS

    DIFFERENCE 391 FPS

    DIFFERENCE/INCH 130 FPS PER INCH

    10.5" 2755 FPS ... 14.5" 2984 FPS

    DIFFERENCE 229 FPS

    DIFFERENCE/INCH 57 FPS PER INCH

    14.5" 2984 FPS ... 16" 3075 FPS

    DIFFERENCE 91 FPS

    DIFFERENCE/INCH 61 FPS

    16" 3075 FPS ... 18" 3245 FPS

    DIFFERENCE 170 FPS

    DIFFERENCE/INCH 85 FPS

    18" 3245 ... 20" 3254 FPS

    DIFFERENCE 9 FPS

    DIFFERENCE/INCH 4.5 FPS

  6. #6
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    Default Re: 55gr vs 77gr Data

    With some of the basic data/info previously provided by forum members, you can make your own ballistic cards here for free:

    http://www.jbmballistics.com/cgi-bin/jbmcard-5.1.cgi
    Last edited by bamboomaster; September 13th, 2017 at 06:48 PM.
    - bamboomaster

  7. #7
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    Default Re: 55gr vs 77gr Data

    Quote Originally Posted by bamboomaster View Post
    With some of the basic data/info previously provided by forum members, you can make your own ballistic cards here for free:

    http://www.jbmballistics.com/cgi-bin/jbmcard-5.1.cgi
    That's a nice ballistics program thanks for posting that link .

  8. #8
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    Default Re: 55gr vs 77gr Data

    Here is a BUNCH of factory round Chrono data... from my 16" and 20" AR15's

    https://www.ar15.com/forums/ar-15/Va...-56/16-676005/

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