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Ballistic Calculators???

 
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Old 01-26-2011, 09:57 AM
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Ballistic Calculators???

I am trying to find 3 or 4 of the best factory loaded ammo for my 300wsm. as I am not set up to reload at this time. I have been using ballistic calculators to help narrow my search. I have been using 165gr. Fusions for the past 3 seasons with good success. My ballistic data was obtained without using tables or calculators but by shooting only and it has proven time and again to be very accurate in both drop and drift. The problem is when I take my proven data and plug it into a calculator everything is way off. Fusion says that bullet has a b.c. of .453 but for me to be able to match the calculated drop to my actual drop I have to drop the b.c. to around .320 and I can't get the drift to match no matter what I do. I have tried for many hours and made sure all the data I am entering into the calculators is accurate including the enviornmental parameters. If I can't take known data and make it work on a calculator how can I trust the given data when shopping for new ammo? It would take me years to buy,shoot, and compare all the different choices out there. I believe the problem to be my lack of experience with calculators because those of you who know how to use them swear by them. If someone can help shed some light this way cuz I'm having trouble seeing!
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Old 01-26-2011, 10:26 AM
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Re: Ballistic Calculators???

Quote:
Originally Posted by shortpants View Post
I am trying to find 3 or 4 of the best factory loaded ammo for my 300wsm. as I am not set up to reload at this time. I have been using ballistic calculators to help narrow my search. I have been using 165gr. Fusions for the past 3 seasons with good success. My ballistic data was obtained without using tables or calculators but by shooting only and it has proven time and again to be very accurate in both drop and drift. The problem is when I take my proven data and plug it into a calculator everything is way off. Fusion says that bullet has a b.c. of .453 but for me to be able to match the calculated drop to my actual drop I have to drop the b.c. to around .320 and I can't get the drift to match no matter what I do. I have tried for many hours and made sure all the data I am entering into the calculators is accurate including the enviornmental parameters. If I can't take known data and make it work on a calculator how can I trust the given data when shopping for new ammo? It would take me years to buy,shoot, and compare all the different choices out there. I believe the problem to be my lack of experience with calculators because those of you who know how to use them swear by them. If someone can help shed some light this way cuz I'm having trouble seeing!
That is a problem that everyone faces if they use the factory BCs.

Those BCs are always Best case scenario and are based on the GI profile because the numbers
are much higher and sell more bullets.

In reality the G7 Profile is closer to the actual performance of the modern bullets but will have
a much lower number.

To me the number does not matter as long as it is accurate from the performance stand point.

The best way is to verify the actual drop with a 100yard zero at 300 and 600 yards and change
the BC number in the computer until it closely matches the actual performance of the bullet/load
combination and use that Number for that bullet/load on all distances and you will be close.

J E CUSTOM
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Old 01-26-2011, 10:57 AM
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Re: Ballistic Calculators???

The first question that came to my mind was how are you getting your velocity data? Published specs are likely to be of so if your not using a crony to get an accurate velocity then I would tweak velocity before BC and see how that goes.
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Old 01-26-2011, 01:14 PM
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Re: Ballistic Calculators???

Welcome to LRH.com From CWT.com

I'll call ya around 14:00 your time.

M
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Long range shooting is a process that ends with a result. Once you start to focus on the result (how bad your last shot was, how big the group is going to be, what your buck will score, what your match score is, what place you are in...) then you loose the capacity to focus on the process.

Last edited by Michael Eichele; 01-26-2011 at 01:19 PM.
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Old 01-26-2011, 01:17 PM
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Re: Ballistic Calculators???

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Originally Posted by bigngreen View Post
The first question that came to my mind was how are you getting your velocity data? Published specs are likely to be of so if your not using a crony to get an accurate velocity then I would tweak velocity before BC and see how that goes.
That's what I was thinkin also
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Old 01-26-2011, 01:48 PM
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Re: Ballistic Calculators???

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Originally Posted by JUDD View Post
That's what I was thinkin also
The answer is I have never shot it through a chrony because when you develope your drop chart by just shooting various ranges without adjusting the turret from 100yd. zero and then measure the drop it does not matter how fast your bullet is traveling. It is a long process however, and that is why I don't want to go through it for every bullet choice available, that would take years. I have tried adjusting the velocity in the calculator without adjusting the b.c., adjusting the b.c. without doing the velocity, and tried adjusting both. The question is how do you compare bullets in a calculator when you don't have a true velocity or b.c. since all the manufacturers are inflating their data? Even if I knew my velocity it would not match what the calculator is saying?
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Old 01-26-2011, 02:02 PM
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Re: Ballistic Calculators???

Quote:
Originally Posted by shortpants View Post
The answer is I have never shot it through a chrony because when you develope your drop chart by just shooting various ranges without adjusting the turret from 100yd. zero and then measure the drop it does not matter how fast your bullet is traveling. It is a long process however, and that is why I don't want to go through it for every bullet choice available, that would take years. I have tried adjusting the velocity in the calculator without adjusting the b.c., adjusting the b.c. without doing the velocity, and tried adjusting both. The question is how do you compare bullets in a calculator when you don't have a true velocity or b.c. since all the manufacturers are inflating their data? Even if I knew my velocity it would not match what the calculator is saying?
We shoot the rifle through a Chrono and that takes one variable out of question. Then shoot at various ranges to compare the drop chart with the advertised BC. Adjusting the BC to and Fro to get the curve that best matches our chart.
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