velocity

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by D Scott, Aug 28, 2011.

  1. D Scott

    D Scott Well-Known Member

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    I am getting started into reloading now for about a year, I dont have a chronograph yet but am working off the reload data in the reloading books to estimate bullet speed, (MV) the test barrels are 24 " mine are 26 " I'm shooting a 260 rem, and a 22-250 is there any rule of thumb to estimate velocity from 2 inch extra barrel ? Thanks in advance Scott
     
  2. Fitch

    Fitch Well-Known Member

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    I've found MV can differ from published MV by a surprising amount even in the same length barrel. I'd even go so far as to say the published MV are frequently almost useless beyond the conclusion that more powder will make the bullet go faster, and this powder might be faster than that powder.

    The same load can differ by 150 fps between two rifles of the same barrel length. IMO, there really isn't any good alternative to measuring MV if one want's to know how fast the bullet is going.

    Fitch
     

  3. D Scott

    D Scott Well-Known Member

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    thanks for the heads up, I will try to get use of a chrono and get it dialed in a little more tight, I thought the books might be a little closer.gun)thanks Scott
     
  4. trebark

    trebark Well-Known Member

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    While I generally agree with Fitch, I would add that in-general you gain/lose about 20-25fps per inch of barrel.

    Chrono is a relatively inexpensive tool to acquire. They start around $90. Here's the one I use with good results...

    Shooting Chrony F1 Master Chronograph - MidwayUSA
     
  5. D Scott

    D Scott Well-Known Member

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    thanks for the feedback, I guess Im going to pony up $ and just get one, but that leads me to another question, is there any value in doing load development at 50 yrds vs 100 yrds to reduce the human error variable ? my goal is to work up to 1000 yrd distance lightbulb thanks Scott
     
  6. trebark

    trebark Well-Known Member

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    Although many conduct load development at 100 yards, best results will be seen at 200 or 300 yards.

    For instance, I will often conduct my initial load development with the chronograph at 100 yards. Then when I find a load that I think is working (provides .5moa groups or better and a low extreme-spread), I will then stretch out to 200+ in order to truly determine accuracy and confirm velocity data.
     
  7. D Scott

    D Scott Well-Known Member

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    Thanks for the advice
     
  8. Fitch

    Fitch Well-Known Member

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    Same here. If one want's to shoot something way over there, one has to know how the ammo works when aimed at something way over there. :)

    My varmint rifles (except the Hornet and .17HMR) and my .30-06 deer rifle are zeroed at ~200 yards.

    Fitch
     
  9. rscott5028

    rscott5028 Well-Known Member

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    It won't reduce human error. It simply obscures it.

    As for published velocities, you'll notice that you're own velocity will go up or down with changes in seating depth (i.e. amount of jump to the lands).

    Even though Chrony's aren't perfect, they are a great tool. You won't be sorry.

    -- richard