Hornady "American Gunner" 308 velocities?

Discussion in 'Rifle' started by Mikaveli, Jan 16, 2017.

  1. Mikaveli Member

    Member Since:
    Jan 1, 2016
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    Hornady claims 2700 fps for its 158gn 308 ammo.

    According to the MagnetoSpeed chronograph, I'm averaging just 2520 fps.

    Their test barrel is listed as 24" - same length as mine. 180 fps seems a big drop on the claimed muzzle velocity?

    Is this normal - what else could explain the loss?
  2. boostless Active Member

    Member Since:
    May 5, 2014
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    I don't see what rifle/length you are shooting but it's a "standard" of 50 FPS per inch lost.
  3. Mikaveli Member

    Member Since:
    Jan 1, 2016
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  4. boostless Active Member

    Member Since:
    May 5, 2014
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    Higher quality barrel? Elevation, temperature, or other environmental conditions?

    If I remember correctly they do all of their testing in an underground or indoor facility.
  5. spamassassin Well-Known Member

    Member Since:
    Aug 8, 2014
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    Most ammo manufacturers test in a pressure test barrel. These are not what you see on rifles and typically are very tight so pressures are going to be at their peak for them. How they're getting 2700fps is not a huger mystery. That's normal for a normal pressure .308. How you're not getting it, and this is just an educated guess: The chambers on MVP's are set for NATO spec which makes them hotdog-in-a-hallway status for commercial ammo meaning you're not going to develop the pressures that Hornady did in their super tight test barrel. 200fps does seem like a lot though so I'm also going to guess someone at Hornady was taking, shall we say, subtle liberties with the facts inasmuch as those facts don't seem to represent the truth, the whole truth and nothing but the truth.
  6. Mikaveli Member

    Member Since:
    Jan 1, 2016
    Message Count:
    43
    Results so far (ignore the average / SD):

    14844278797902.jpg

    Well, I'm going to retest - I want to see how much variance there is between a clean, cold barrel - and at the end of a day at the range etc.

    It's been pretty cold here - so I'm guessing a hot summer day will see a measurable difference (no idea how much)?

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