Fast Barrel on my Cooper?

Discussion in 'Long Range Hunting & Shooting' started by 8andbait, Aug 14, 2012.

  1. 8andbait

    8andbait Well-Known Member

    Jan 14, 2012
    Is it possible for barrels of the same length to be 100-150 fps faster than each other?

    According to drop data out to 400 yards my 6.5 creedmoor is at 2840 fps when it should be 2710 according to Hornady Data.

    Factory Hornady 140 gr AMAX.

    zeroed at 200
    300 yards is up 2.0 MOA
    400 yards is up 4.5 MOA

    supposed to be
    300 yards up 2.5
    400 yars up 5.25

    According to this my velocity is 2840

    Any thoughts? 130 fps more out of the same length barrel seems extreme.

    Not complaing, very happy if it's true.

    thanks, gary
  2. elkaholic

    elkaholic Well-Known Member

    Dec 4, 2008
    It's not impossible but highly unlikely if you are talking same barrel length. More than likely, there is some combination of input error such as zero, scope height, etc. which is affecting your drop numbers.....Rich

  3. rscott5028

    rscott5028 Well-Known Member

    Apr 18, 2010
    it's not just the barrel length that matters if comparing to published load data

    diferences in chamber+brass+temp+altitude+powder lot+twist rate and/or chrony error can all cancel or stack up to easily 150+/- fps

    in fact, it doesn't look like you're using a chrony
    rather, it appears you're calculating mv off of come-ups vs POI

    so, now you've got possible error in published scope adjustment per click vs actual, plus sampling error from group sizes, variable MV SD/ES, and published vs confirmed BC

    you're actually not doing bad

    just keep shooting without making changes and make sure everything is consistent before you adjust

    -- richard
  4. 8andbait

    8andbait Well-Known Member

    Jan 14, 2012
    cool, thanks

    I really do need a chronograph.
    Also need somewhere I can shoot longer than 400 yards.

    I have done alot of calculations and zeroing. The current combination seems to be working very well together and faster than anticipated which for me is just fine :D

    we will see what the future brings.

    thanks, gary