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new retro project, velocity ?

Discussion in 'Rifle Discussion' started by peabody, Nov 21, 2010.

  1. peabody

    peabody midwest New Member

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    howdy.

    i've picked up a m16A1 pencil barrel, but somewheres in its past' someone cutt her back to 18.5 inches.

    rifling looks very good' i'm having steve at adco re-crown and re-thread.
    its a 1/12 twist, so i'll pretty much only use 55 grainers.

    my question is, what kind of velocity can i expect with federal XM193F ammo ?
    out of a 18.5 inch barrel ?


    peabody
     
  2. usmc

    usmc oregon Active Member

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    you usually gain 30 fps past 20 inch's.in the reverse you youve lost maybe 60 to 100 fps. but if accuracy is the game the slower fps may work out best.