chrono velocity questions

Discussion in 'The Ammo & Reloading Forum' started by trutta, Feb 27, 2011.

  1. trutta

    trutta New Member

    Feb 27, 2011
    I own an M77 UL with a 20" barrel and bought some Hornady Superperformance 95gr loads that promise 200fps gain, and the company vid claims that barrel length differences should be negligable due to their special powder mix.

    My shooting buddy just got a chrono!

    The factory claim is 3185fps. I got a pretty consistent average of 2760fps, meaning I'm 200 below "normal" and 400 below "superperformance".
    Factors were:

    -20" barrel
    -cold day (28F)
    -elevation (8600ft)

    Comments? (Like "Don't believe everything you read?" lol) How much of a factor is temperature?

    I did get a 1" group:).
    Last edited: Feb 27, 2011
  2. woolleyworm

    woolleyworm Active Member

    Feb 23, 2009
    SW Fort Worth
    When the test temp is probably around 75*, temp is ALOT ! What was your ammo temp? Often if it is really cold, I'll keep rounds in my shirt pocket to keep them warm. 28* is pretty chilly.
  3. 312shooter

    312shooter Well-Known Member

    Mar 17, 2008
    Las Vegas NV
    One word...... Marketing
  4. carver

    carver Moderator

    Jul 28, 2008
    DAV, Deep in the Pineywoods of East Texas, just we
    Results may vary!
  5. jdon72

    jdon72 New Member

    Feb 3, 2009
    I have found that many companies put their max velocity in their target group as their stated velocity. So, while you shoot 100 rds and one hits the highest, that is what they put. it is not the average. Unfortunately, many companies do this.

  6. dksac2

    dksac2 New Member

    Jan 14, 2011
    The company's shoot their loads from a rail gun, long barrel and ideal conditions.
    What you get is what you get. A lot of variables. Temp, altitude, firearm, barrel length, same components, and more than a few other things.
    I have never got the advertised velocity the ammo company's claim from my firearms.
    Crono's are one of the best tools for reloaders.

    John K
  7. JLA

    JLA Well-Known Member

    Feb 26, 2007
    Heart Of Texas
    What in the world are you complaining about. MOA is a good thing no matter the velocity.

    Barrel length will affect velocity. It doesnt matter what powder the round is loaded with, you simply cant bend or break the laws of physics...

    Temp will affect powder burn, the colder it is the slower it burns, this could also explain some of the velocity loss. id be willing to bet, at 28 degrees with such a short barrel, you still had unburned powder leaving the barrel behind the bullet. That powder not burning lowers the pressure curve and directly affects velocity. again, physics, powder burning creates heat and heat creates pressure in the form of hot expanding gasses, and the pressure is what drives the bullet.

    Dont believe everything you read. Somewhere on that box youll find the words..."individual results may vary" that simple statement releases them from all liability regarding actual product performance...
  8. 308 at my gate

    308 at my gate New Member

    Dec 6, 2008
    Lost in SW USA.
    I agree barrel length does make a difference no matter what the powder is. I have a chrono myself that I use for reloads and even the velocities in the reloading manuals are only good for their particular gun, temp, primer, brass, altitude, powder, and bullet design. The Variables go on and on. But like JLA indicated, that the rounds are very consistant giving you MOA, which is even better.
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