Home Forums Hunting & Shooting Ask The Gunwriters Velocity without chronograph?

A GOB on another board asked:
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<br>"With all the different variables known, and just measuring bullet drop from different ranges can you work backwards to come up with your velocity?"
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<br>Answered him there of course but figured I should answer his question here too. So here's my answer, in case it's of interest to anyone here --
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<br>About fifty years ago, I read of a way to determine mid-range velocity without any special instrument. When I later wanted to read that write-up again, I couldn't find it. So I figured-out, from scratch, how to do it using basic physics and trigonometry (with just a thermometer to read range air temperature and a tape to measure distance, plus some kind of "target" to ring or clang when the bullet hits it). I developed a set of tables too -- rather tediously, in those old precalculator days of pencil, paper, and slide rule. Still have my old write-up, tables and all, somewhere in this midden that I live in. It turns-up now and then, when I'm looking for something else.
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<br>Basically, you find the point horizontally perpendicular to the trajectory, along a line even with the target, where an observer hears the sound of the muzzle blast and the sound of the bullet's impact at the same time. Then you can calculate the time of flight from the target distance, observer distance, and speed of sound -- which varies with air temperature.
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<br>The method works pretty well but is a good bit more bother than it's worth. And it estimates the average velocity between the muzzle and the target, not muzzle or near-muzzle velocity. So now I have a couple of Oehlers and have happily left the old triangulation method deep in my memory and old notes.
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<br>Go with nothing less than or other than an Oehler 33* and don't look back. Or sideways.
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<br>*typo -- meant to say "Oehler 35"

Now Ken there is an easier way to do it without all that figuring. Just set up and shoot and as soon as you touch her off jump in your old Chevy pickup, slap her in drag and goose it. When you catch up with the bullet you jus' look at the speedometer.
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<br>BCR
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<br>ps. It helps to already have the motor running before you shoot.

<br>Ken, considering that a bullet traveling at 2800fps takes 0.111 seconds to cover 100 yards, and a bullet traveling at 3300fps takes 0.094 seconds to cover the same distance, someone would need tremendously accurate reflexes to judge the difference. You would need uncanny precision to gage the impact of the bullet and crack of the rifle. A few thousandths off either way and you would miss the velocity by 500fps+/-.
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I have always found that the velocity from my chronograph is what it's supposed to be. That the estimated velocity from handbooks seems quite close all of the time. That said I have had a chronograph since the 1960's.
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<br>I made a ballistic pendulum that worked well with .22's. Those are free you know.

I always bow in awe and respect before those who can consider a new and unfamiliar matter for only a few seconds and immediately know more about it than I can figure-out through hours and days of hard thinking and study. It's down-right humbling the way such whiz-brains invariably and so quickly find flaws in my conclusions, flaws that completely escaped my close consideration of every detail that I could think of to consider. Someday, maybe, I'll accept my stupidity as inescapable.
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<br>In the above matter, I was influenced by the fact that the human ear can detect an incongruity of nearly simultaneous sounds within -- oh, what the heck! I HAVE to be wrong if a whiz-brain says so. I accept correction. I bow. I slink away in humility.

Ken,
<br>You should of at least thought of using the pick-up:)

<br>Ken - Nice response. I guess it is easy for you to tell the difference between .02 seconds and .05 seconds. My reflexes just aren�t that good.
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<br>I should have known not to question you. It won�t happen again I can assure you.
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"Reflexes?"
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<br>Perception.
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<br>My reflexes aren't good enough for me to respond to a stimulus in 1/1000 or even 1/500 second, but my perception is good enough for me to see a burst of light from an electronic flash -- as short as 1/100000 second or less. I can also see the brief opening of a leaf shutter set for 1/500 second. So can you.
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<br>Reflexes have nothing to do with the matter in question. Perception does. Anybody can perceive brief incongruities of timing, just as anybody can perceive brief intervals.
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<br>And nowhere have I claimed great accuracy for the method, so it's silly to imply that my method is worthless because it's less accurate than a well set-up chronograph.

Zerodrift, what do you think makes music such a wonderfull thing? It sure as dog do is not your reflexes. You do not gather up all the sounds and shove them in to your head for processing, no it is the preception as Ken puts it you are able to precieve the distinct difference in timing long before you can react to it. This is why the human brain is still the champ no computor can yet compare. Why does a strobe light work? can you react faster than a strobe,no but you see it and it registers in your brain long before you can physically react. Give it some thought.
<br>Does any one Remember Joe Isuzu and his out running a bullet, now there was a guy with fast reflexes.
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<br>Bullwnkl

I once knew a fellow whose reaction time was longer than his attention span.....by the time he realized something happened, he had forgotten what it was
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<br> This idea sounded very familiar. I found it finally in Sharpes "Complete Guide to Handloading". So there Ken, you are not nuts after all.
<br>Good luck!

<I once knew a fellow whose reaction time was longer than his attention span.....by the time he realized something happened, he had forgotten what it was.>
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<br>Forgive me... I didn't know we had met.
<br>Russ