Read an article about the need to recalculate your BC before the bullet goes transonic somewhere around 800 yards for a 168grFed match BTHP. It said to crono 20 shots then determine the difference btwn POA and POI. Then it said to " <span style="text-decoration: underline">take that info and determine your new BC</span>". HOW ??,The Author does not explain how to do that. How do you use that info to determine a new BC. Let's say I am 23 inches high and 18 inches left of POA. How does that info translate into a new BC. I will be using the Kestrel w/ Atrag. I can not see where this unit offers an input for a G7 BC. Let's just say I learn how to determine a new BC, Where do I input it too ? Into the G1 BC ? Would appreciate some help here.
Advanced Marksmanship How do I calculate a down range BC ?
- Thread starter lobster
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Re: How do I calculate a down range BC ?
The advice to join the online training is good.
Theoretically computing a new BC is simple: you either measure velocity at the muzzle <span style="text-decoration: underline">and at the target</span> a few hundred yards down the range, or (less precise but easier to accomplish) measure muzzle velocity and the actual bullet drop at the target. Then you <span style="text-decoration: underline">plug that data into a ballistic calculator or program</span> such as Bullet Flight (or other programs, i.e. Quick Target Unlimited) - and <span style="text-decoration: underline">it will compute the new BC for you</span>. Your Atrag probably just doesn't have this capability, I don't know.
Unless you're already a pretty good shot (or your BC is G1 and comes from a manufacturer's brochure), I'd buy Bryan Litz book which lists banded G7 BC for many long range bullets and use those for the time being. <span style="font-style: italic">In fact I put my money where my mouth is, and bought that book myself. Eyeing the 2nd edition.</span>
The advice to join the online training is good.
Theoretically computing a new BC is simple: you either measure velocity at the muzzle <span style="text-decoration: underline">and at the target</span> a few hundred yards down the range, or (less precise but easier to accomplish) measure muzzle velocity and the actual bullet drop at the target. Then you <span style="text-decoration: underline">plug that data into a ballistic calculator or program</span> such as Bullet Flight (or other programs, i.e. Quick Target Unlimited) - and <span style="text-decoration: underline">it will compute the new BC for you</span>. Your Atrag probably just doesn't have this capability, I don't know.
Unless you're already a pretty good shot (or your BC is G1 and comes from a manufacturer's brochure), I'd buy Bryan Litz book which lists banded G7 BC for many long range bullets and use those for the time being. <span style="font-style: italic">In fact I put my money where my mouth is, and bought that book myself. Eyeing the 2nd edition.</span>
Re: How do I calculate a down range BC ?
Thanks mouse07410 for the info provided. I am going to look further into the programs you mentioned and do plan on acquiring Bryan Litz's book as well. Frankly , I am not very comfortable setting up my crono down range, My luck, I would inenvertenly hit it !!! As far as on line training , I have yet to see any instruction along this line offered. Perhaps I have missed it. Thanks again though.
Thanks mouse07410 for the info provided. I am going to look further into the programs you mentioned and do plan on acquiring Bryan Litz's book as well. Frankly , I am not very comfortable setting up my crono down range, My luck, I would inenvertenly hit it !!! As far as on line training , I have yet to see any instruction along this line offered. Perhaps I have missed it. Thanks again though.
Re: How do I calculate a down range BC ?
Lobster, the online training is a sub forum on this site that is a subscription service. It's well worth your money to join.
Lobster, the online training is a sub forum on this site that is a subscription service. It's well worth your money to join.
Re: How do I calculate a down range BC ?
Well blklabs, your the 3rd person now to make that suggestion to me. So I hear you guys loud and clear. I will look into it. Thanks for the suggestion.
Well blklabs, your the 3rd person now to make that suggestion to me. So I hear you guys loud and clear. I will look into it. Thanks for the suggestion.
Re: How do I calculate a down range BC ?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: lobster</div><div class="ubbcode-body">Thanks mouse07410 for the info provided. I am going to look further into the programs you mentioned and do plan on acquiring Bryan Litz's book as well.</div></div>
IMHO - money very well spent. Even though Bryan didn't provide enough of ballistic data for one to be able to write a complete - even simplified - calculator. The info he gives is very useful - and the actual BC for many bullets are priceless.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Frankly, I am not very comfortable setting up my crono down range, My luck, I would inenvertenly hit it!!!</div></div>
Don't feel bad! Many of us (me definitely included) feel (and are
) the same way.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">As far as on line training , I have yet to see any instruction along this line offered. Perhaps I have missed it.</div></div>
Check this thread.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: lobster</div><div class="ubbcode-body">Thanks mouse07410 for the info provided. I am going to look further into the programs you mentioned and do plan on acquiring Bryan Litz's book as well.</div></div>
IMHO - money very well spent. Even though Bryan didn't provide enough of ballistic data for one to be able to write a complete - even simplified - calculator. The info he gives is very useful - and the actual BC for many bullets are priceless.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Frankly, I am not very comfortable setting up my crono down range, My luck, I would inenvertenly hit it!!!</div></div>
Don't feel bad! Many of us (me definitely included) feel (and are
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">As far as on line training , I have yet to see any instruction along this line offered. Perhaps I have missed it.</div></div>
Check this thread.
Re: How do I calculate a down range BC ?
Lobster it sounded like you weren't familiar with the online training section. Just trying to help you out, not be repetitive. Good luck!
Lobster it sounded like you weren't familiar with the online training section. Just trying to help you out, not be repetitive. Good luck!
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