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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/30/2008 at 09:24
trigger29 View Drop Down
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X = 180 Y = 90 (X+Pyro)+(Y-Pyro) = ?

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I was wondering if there is a way I can calculate muzzle velocity by knowing the ballistic coefficient, and drop at several ranges. I know it won't be accurate like a chrono, but I don't have one of those. My other option is keep plugging numbers in to a ballistic calculator until it spits out the drop numbers I have.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/30/2008 at 09:35
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can we get one of them ingineer fellars over hereBuckyHowdy
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/30/2008 at 09:41
trigger29 View Drop Down
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X = 180 Y = 90 (X+Pyro)+(Y-Pyro) = ?

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exactly. Dale Clifford will probably answer me, and I still won't understand.

Edited by trigger29 - December/30/2008 at 09:42
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/30/2008 at 09:52
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yes there is give me the drop from 200 yds, to 300 yds and I don't need the BC (its implied in the drop)
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/30/2008 at 10:01
trigger29 View Drop Down
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X = 180 Y = 90 (X+Pyro)+(Y-Pyro) = ?

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Originally posted by Dale Clifford Dale Clifford wrote:

yes there is give me the drop from 200 yds, to 300 yds and I don't need the BC (its implied in the drop)
 
I don't have it yet. Jeez Dale it's cold out there. Wind is blowing about 35 mph. Drop at 300 is about 18"left.
 
Is there some super secret formula I can use once I shoot them?


Edited by trigger29 - December/30/2008 at 10:01
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/30/2008 at 13:45
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not at all -- do it the same way as swaro does on their web site, by grouping all calibers that have the same drop from (100 yd zero)  from 200 to 300 yds in a thing they call the hit factor. , this same method is used in exbal programs to adjust the mag. on reticles for the bar holds, also knowing this you can figure out what the turret on the redfield is set , as it was calibrated the same way
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/30/2008 at 13:51
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why cant smart people like that run the country???
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/30/2008 at 14:12
trigger29 View Drop Down
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X = 180 Y = 90 (X+Pyro)+(Y-Pyro) = ?

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Originally posted by Dale Clifford Dale Clifford wrote:

not at all -- do it the same way as swaro does on their web site, by grouping all calibers that have the same drop from (100 yd zero)  from 200 to 300 yds in a thing they call the hit factor. , this same method is used in exbal programs to adjust the mag. on reticles for the bar holds, also knowing this you can figure out what the turret on the redfield is set , as it was calibrated the same way
 
That's exactly what I need it for. I need to set mag. on my Rapid-Z. Is there anywhere I can do this, or do I need exbal?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/30/2008 at 14:59
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Originally posted by pyro6999 pyro6999 wrote:

why cant smart people like that run the country???


Because we need them to live above ground............grin
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/30/2008 at 16:33
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  t29, Don't know if your still interested but if you know the b/c of your bullet plus have the bullet impact measurements above and below target center at several distances(do from 200yd to 500yd w/a 100yd zero)you can match your info to the ballistics data in a Speer reload manual.  They catagorize their data by ballistic coefficients. So simply find your b/c in the Speer data,match your trajectory numbers to Speers under that b/c and see what velocity they used to get that trajectory. Crude but should get you close and it might beat plugging numbers into a computer.
  Now! Anyone that shoots as much as you and spends big $$$$$$$$$$$$$$$$$$$ on scopes oughta have a Chrony. Bought mine back in the 80's and it's still gettin it done. LOL
  Hope this is helpful.
 
til later
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/30/2008 at 16:40
trigger29 View Drop Down
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X = 180 Y = 90 (X+Pyro)+(Y-Pyro) = ?

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I don't handload bubba. This is the start of it. Anybody who shoots as much as me......like 20 boxes a summer, should load their own. That was an expensive summer. I have somebody loading some for me now, but he doesn't have a chrony either. I doubt the little hand held one I have for my paintball gun will cut it. If it will, I'll take volunteers to hold it.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/31/2008 at 08:48
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have you tried the ballistic program on the zeiss website--- it does the same thing as the swaro, but the explanation is from a slightly different marketing perspective.??
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/31/2008 at 11:42
trigger29 View Drop Down
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X = 180 Y = 90 (X+Pyro)+(Y-Pyro) = ?

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Originally posted by Dale Clifford Dale Clifford wrote:

have you tried the ballistic program on the zeiss website--- it does the same thing as the swaro, but the explanation is from a slightly different marketing perspective.??
 
 
I would like to, but the easiest way would be to input my muzzle velocity and B.C.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/31/2008 at 11:47
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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/31/2008 at 12:00
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You can find the required tables on the internet.

The calculation can be performed thusly:

Known drop (measured) from say 200 to 300 yards in inches divided by distance an object will drop due to acceleration of gravity (approximately 193 inches) equals time squared. 

Take the square root of time squared to get the TIME OF FLIGHT  (TOF)

Divide 300 feet (100yds) by the TOF  to get MEAN VELOCITY in 100yds (200-300yd)

Mean Velocity over 100yds EQUALS ACTUAL VELOCITY at 50yds (which in this case will be at 250yds)

You will need the tables calculated by Professor Francis Bashforth in “A Mathematical Treatise on the Motion of Projectiles, founded chiefly on the Results of Experiments made with the Author’s Chronograhph, specifically,  “A General Table of values of  d2/w (t) for Ogival-headed Shot” .   From the table find the number which correlates to your Actual Velocity.   To that number, add the (distance in feet (750) times the Air Resistance Factor) determined by (bullet Diameter squared  (d2 )  Divided by (Bullet Weight in grains  times 7000 >( Bullet weight in pounds (w)))).  Go back to Bashforth’s tables and find the corresponding Velocity (corresponding to the number result from your calculations)which will be your Muzzle Velocity.  

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/31/2008 at 12:04
trigger29 View Drop Down
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X = 180 Y = 90 (X+Pyro)+(Y-Pyro) = ?

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Ok well thanks for the link Doug. Unfortunately that will have to wait until I go back to work. I can feel the bankers hand around my neck already. That's an excellent formula KB. Too bad I'm retarded, and probably won't be able to make it work. We'll see when I get out to shoot. I'll try it.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/31/2008 at 12:12
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Send me your bullet info and measured drop and I'll do the calculations for you and send you an example "method" you can use in the future.  That way, once you have Bashforth's tables, you can do it with a hand calculator and won't have to depend on external calculators.  It is a pretty straight forward method.  When measures are very accurate and all the decimal places are taken into consideration, it has been shown to be accurate to within +- 1fps from measured with a chrono.  
Chrono is EASIER, though.  
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/31/2008 at 13:15
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it would be easier to simulate it in JBM.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/31/2008 at 13:34
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It IS easier, but less aesthetically and esoterically pleasing.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/31/2008 at 16:51
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Hey trigger
 
Give us whatever data you have and let us experiment with the RapidZ calculator, like what drop what bullet and what ballistic coefficient.  There may be a way to do it with a regular ballistics program also. 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/08/2009 at 13:06
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 A buddy ran some slugs over my chrony last Fall that advertised 1900fps on the box. They were consistantly 200fps+ slower than that. I think it was 250 or so. I do realize you would have to duplicate their test peramiters to give a more honest comparison.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/08/2009 at 16:49
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Aesthetics, schmesthetics...that's just too much thinking when you can simply push the buttons on the front of the chrono and (if you haven't shot it) get all kinds of fun numbers. I just got one for Christmas...haven't had an opportunity to take it to the range but I've run some rubber bands over it in the back yard (up to 138 fps, by golly).
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/09/2009 at 01:36
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When the thread said" Hey smart people" I immediately thought you were talking to me, but after reading the question and seeing the answers I realize you are looking for someone else.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: January/09/2009 at 11:31
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