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Started by HollywoodMarine, January 24, 2011, 04:05:26 PM

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HollywoodMarine

January 24, 2011, 04:05:26 PM
Thought I would pass it along.

"A bullet's dispersion is usually initiated at the muzzle, as a small velocity component that's perpendicular to the intended flight path (up, down, left, or right). If that velocity component results in a miss distance of .25" at 100 yards, you can calculate how much miss distance there will be at 1000 yards by looking at the ratio of flight times.

For example, if the bullet strays .25" at 100 yards, where the flight time is .111 seconds, at 1000 yards, it will have strayed by .25*1.632/.111 = 3.7". 1.632 seconds is the flight time to 1000 yards. Note the bullet does not stray by the 2.5" you would expect by multiplying .25" by 10.

This same logic goes for group sizes as well. If you can shoot a .5" group at 100 yards with your rifle, the best you can expect to do at 1000 is 7.4" under ideal conditions and zero MV variation.

This dispersion model assumes that aiming error is not a significant part of the dispersion. If there is an aiming error, it will have a perfectly linear effect, meaning .5" at 100 yards translates to 5" at 1000 yards."
A wise man can learn from a fool, but a fool cannot learn even from a wise man.

Embrace the suck!

Pvt.Joker

#1
January 24, 2011, 10:41:21 PM
Good info, Hollywood.

For us "conceptual learners", this boils down to the ballistic equivalent of "Murphy's Law":
"Whatever can go wrong, will go wrong, and at the worst possible moment."
The earlier an outside force acts on a projectile, the more influence it exerts.

Sound about right?

(This explains why the slightest damage to the muzzle is disastrous, as well.)
"The battlefields of history are littered with the bones of those, who, at the dawn of victory, sat down to rest; and, resting, died."   
"We can't guarantee success in this war, but we can do something better. We can deserve it."
-John Adams, in a letter to his wife, Abigail.

George63

#2
January 24, 2011, 10:46:19 PM
for most folks it is easier to use an online ballistic calculator for bullet drop, they will also do wind drift

Baminal

#3
January 24, 2011, 11:24:03 PM
Until I get the web access kit built into my M1A, I guess i will still have to use my own brain to do the math.

The death of democracy is not likely to be an assassination from ambush.  It will be a slow extinction from apathy, indifference and undernourishment.
Robert Maynard Hutchins, Educator (1899-1977)

Love you liberty and fight for it like men who know its value.  Once lost, it will never, never be regained.
Capt. Hugh Ledlie (1720-1798)

Pvt.Joker

#4
January 25, 2011, 06:46:33 PM
Quote from: Baminal on January 24, 2011, 11:24:03 PM
Until I get the web access kit built into my M1A, I guess i will still have to use my own brain to do the math.



?...mine came with an r-45 jack under the butt-plate...



:D

"The battlefields of history are littered with the bones of those, who, at the dawn of victory, sat down to rest; and, resting, died."   
"We can't guarantee success in this war, but we can do something better. We can deserve it."
-John Adams, in a letter to his wife, Abigail.

Texas Rifleman

#5
January 25, 2011, 06:56:27 PM
Where did you get that data ?
...when the student is ready, the teacher will appear.
Davilla - 5/09

sparks1

#6
January 25, 2011, 07:12:01 PM
Quote from: Baminal on January 24, 2011, 11:24:03 PM
Until I get the web access kit built into my M1A, I guess i will still have to use my own brain to do the math.



I saw a phone with a ballistics program on it, also an Ipad(?) with one. Even gave shooting angle come ups . Ipad...what ever gizmo that Apple has that is not the phone or the big screen gizmo. I think it's availible for most the smart phones.

Best to know the math...batteries fail at the worst times.
Integrity is easier to keep, than to regain.

The Truth is that teamwork is at the heart of great accomplishment. 
(John Maxwell)

Wheeler44

#7
January 25, 2011, 07:51:42 PM
Quote from: sparks1 on January 25, 2011, 07:12:01 PM
Quote from: Baminal on January 24, 2011, 11:24:03 PM
Until I get the web access kit built into my M1A, I guess i will still have to use my own brain to do the math.



I saw a phone with a ballistics program on it, also an Ipad(?) with one. Even gave shooting angle come ups . Ipad...what ever gizmo that Apple has that is not the phone or the big screen gizmo. I think it's availible for most the smart phones.

Best to know the math...batteries fail at the worst times.

The luddites that I hang with just want to know how much to hold over, beyond their 275 yd. zero...
"Appleseed,  putting the second amendment into the hands of American citizens."     -Mrs. Wheeler

"We intend to produce men who are able to light a fire for Liberty in men's minds, and make them the finest rifle marksmanship instructors on the planet."   -Son of Martha

voortrekker

#8
January 25, 2011, 10:34:57 PM

Here's a tool to consider to get you and your zeroed centerfire rifle on point of impact at given distances.

It is a software, whereby, you can download it to your PC or as an iphone application.

I have used it for deer hunting at longer ranges.

This software works well and I am glad I found it.  The software encompasses very, very many popular rounds and even further goes into calibers of different projectile weight and can be used for custom reloads.

Wind drift, humidity, elevation, temperature, etc, etc, etc......this software is really good.

However, there is no ballistic software to my mind that can give you better data, than with your rifle and ammo AND you shooting it than real experience with your equipment........there is absolutley no substitute in my experience.

Ballistic software, of any kind, presently, is a tool, a stepping stone, to help fine hone the ballistics of your rifle, in your hands.

ballistic.zdziarski.com/

The software can be downloaded directly to your PC    -OR-     if you have an iphone or itunes, a person can use itunes to buy and download this software as an application to your iphone.

Lastly, this software is a great tool for those that endeavor to hit targets at longer distances.  With this being said, I STRONGLY recommend if you use this software, do not depend on a iphone or a hand held electronic device to keep this information for you.

If you use the data from this software, keep hard paper print outs, hopefully weather proofed to your rifle stock.

Why do I say this?

We all know that at Appleseed shoots, we shoot, rain or shine(unless there's lightening abound). 

Therefore, we cannot depend on electronic devices when it rains at shoots when we are doing KD instruction.

Heads up and I hope this helps.


Brett
If YOU are thinking, WE are winning.

SamD

#9
January 26, 2011, 01:03:14 AM
QuoteWith this being said, I STRONGLY recommend if you use this software, do not depend on a iphone or a hand held electronic device to keep this information for you.

If you use the data from this software, keep hard paper print outs, hopefully weather proofed to your rifle stock.

Something you will learn from more formal disciplines is using a scorebook.
I highly encourage it.

For fun you can use this as a filler page in a binder till you buy one that suits

Pretty self explanatory, email if you can't figure it out
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