My take on bullet bc testing

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by goodgrouper, Apr 7, 2009.

  1. goodgrouper

    goodgrouper Well-Known Member

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    Being an avid ultra long range shooter/experimenter/competitor as well as a short range shooter/experimenter/competitor has given me a unique view of the bullet bc testing methods. As I have traveled all over the west to different shooting ranges and areas, I have seen some eye opening things as far as this is concerned. What I have seen is that basically, you cannot get absolute bc data from any one place at any one time.

    I have shot at one area that no matter what caliber or bullet used, you will impact 2 moa low at 1145 yards no matter what the conditions. Day in day out over years of trials, this is the constant result at this place. Then in another place, 1400 yard shots require compensation of a 1200 yard shot with every gun on every day several years running. Add in any scope misadjustment error (which you may have unless you track it throughout it's movement) and you are going to get weird bc numbers. That is the way it is.

    Now switch gears to short range where scopes aren't used for adjustment so we can throw that error right out. Yet we find the same thing. Some ranges push bullets down in a headwind, other ranges push bullets down in a tailwind. Some ranges give a little lift with a 3 o'clock wind and some others don't. Some puffs of wind are not created equal and some puffs of wind have a vertical component to them. Ask Gary O' Cock or Walt Berger about flag placement. They will both tell you that they put their flags at strategic places at every different range they shoot at. It all depends on the lay of the land and obstructions etc..

    If you try to isolate a bc from drops at one place, one time, you aren't getting the full story. I'm sorry folks, but that is the facts. I ain't kidding you.

    It takes multiple days, multiple locations, multiple guns, and multiple conditions to get even a ROUGH idea. ANd without wind flags conveying every second of every bit of information, how do you know anything. Then you might say, "well it was dead calm". Well, was it? I can't tell you how many times there hasn't been a breath of wind on my near windflag but my windflag down at 800 yards is moving. Without flags, you ain't a clue. And even if it truly is a dead calm condition the entire trajectory of the bullet, how many times are you gonna get that condition??? Enough to test mutiple guns on multiple days, at multiple locations?? I DOUBT IT! I've been to the range thousands of days in my life and I don't think there's been enough true dead calm days to make a calendar month.

    Basically, you still need to compare your findings with an instrumental method or combination of instrumentals with the range time to get any kind of solid information. So however you want to do it, just make sure you have real world drops from a variety of info, two chronos, computer estimations, Doppler, or whatever. Just make sure you have a comparison of at least two of the combos.

    Just my 2 bits.
     
  2. Michael Eichele

    Michael Eichele Well-Known Member

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    Pretty well sums it up for me too......

    I have come up with different drop data from time to time in the SAME places. Up draft, down draft whatever..........Like you said, multiple days, locations, and most importantly, multiple methods.

    I am working on a double audible clock for time of flight right now. Should be interesting.
     

  3. jwp475

    jwp475 Well-Known Member

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    That about sums it up IMHO