# Please Explain the Math Basics...

Discussion in 'The Basics, Starting Out' started by DixieFreedom, Jan 1, 2004.

1. ### DixieFreedomWell-Known Member

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Dec 26, 2003
Is there a book out there that deals with external ballistics math/simplified?

I need to start at the basic of basics. I have not done any trig since high school. Should I just go get a high school trig book and review it first? I forgot all that stuff, don't really know what the heck subtends means. Milirads and Degrees, all that is trig ain't it? Other than that are trajectory calcs just basic algebra?

But for starts let me outline what I think I know.

1) you gotta know with precision the muzzle velocity of your projectile, B/C, weight.

2)You got to get a trajectory chart

3) You got to know the wind effect

4) Up and down slopes

5) Accurate distance to target

Then it all has to go to adjusting the scope or holding over or off.

Did I forget anything?

So how is all that done lightning fast in the field?

2. ### Michael EicheleWell-Known Member

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3,860
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Jan 6, 2003
1st of all, the only way to shoot accuratley at long range with lightning fast abilities is to KNOW you rifle. Out to 600 yards or so (with a typical 6mm or bigger) the effects of air density by way of barometric pressure, humidity, temprature ect... unless changes are SUPER extreem, will have little effect on the trajectory of you bullet. So if you know your rifle and know your scope in conjunction with the load/rifle combo and have a laser range finder, you can make shots count fast out to 600 yards. After that, unless your a trained proffesional, or have alot of time to practice, you will need to calculate your shot based on the current air density.

There are many computer based ballistic calculators and some usable on a palm pilot that will accuratley calculate ballistics. Including wind, angled shots ect... If you demand to do the long form by way of typical math, you will need to brush up on calculus, algebra, geometry, ect...

Trust me, use the computer.

The Sierra reloading manual has the formulas in them. They also have easy formulas to figure angled shots.

Also "Understanding fire arm ballistics" by Robert Rinker is somewhat usefull in helping in some of these areas.

There are many writings on these subjects. If you need more info, let me know.

Also, it is very needed to have an accurate MV and BC. One should calculate his true MV by adding the distance betwwen the chrony and his muzzle. Army ordinance is .64 FPS for each foot between the muzzle and chrony.

A more accurate way is to use a ballistic calculator.

I think the only thing you forgot is you must know the air density. Factors include, Air temp, humidity, barrometric pressure. Also the BP changes with altitude. You should know the altitude, unless you are mesuring the BP, then the altitude is not important as it is the BP that affects bullet flight and not the altitude itself. Typicaly, the higher you go, the less the BP. All of these factors especially temp and BP have a HUGE impact on 600-1000 yard ballistics.

PS, One way I get set up quick for a feild shot is to constantly moniter your air and I keep several drop charts for a variety of conditions with me. Once my game is located, if I have limited time I use the pre made drop charts, which also have the number of clicks I need to adjust for any given yardage. Also, my drop charts are checked by field testing. Very important.

[ 01-02-2004: Message edited by: meichele ]

3. ### AustinWell-Known Member

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75
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Jan 7, 2004
If you are a math buff like I am, check out http://www.aeroballisticsonline.com It gives you all the equations you could possibly need. I tend to use derivation methods in the calculus and the Newtonian methods seem to work rather well in predicting trajectory for any given projectile, though I am struggling to remember much of my engineering physics stuff to make it work more effectively for me! Trig is a must though to go this route so break out that Trig book and shake off the dust!

TH

[ 01-17-2004: Message edited by: Austin ]

[ 01-17-2004: Message edited by: Austin ]

4. ### Savageman69Well-Known Member

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Oct 1, 2009
I Am using the tajectory zero angle program, i got it emailed to me from this site
I am having some trouble with the parameters, So i have a few questions
What is the bullet impact ht. is that the size of the hole the bullet makes in the target or what. I know its not the target ht. because there is a spot for that,

Also i know published B.C data is using the G1 model regardless of the bullet shape, and thats all fine and dandy. but manufacturers even say we use the g1 model but Scince the g models are old, really old, the G1 model doesnt accurately represent the particular bullet they are testing. I would like to know the B.C decay rates for other bullet models,

or is there a decay rate formula? id think using measurements and the B.C there should be a way to get the decay rate

oh and bullet length thats the length of a new cartrige right? because when i measured the projectile the calculator spit out 110 inches of windage and 50 inches of drop at 100 yds wich is way way off.
and when i measured the whole thing it said .5" wind and 1" drop with my gun sighted at 50 yds wich was alot closer to the results i was seeing.

i usually zero at 125 but i wanted to really test the calculator so i brought it way in
the calculator is within about 1.5" in any direction to what i see at the range

5. ### lomfs24Active Member

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Oct 25, 2009
Just new to this forum so thanks everyone who makes sites like these possible.

I am in a similar boat to the original poster. I have recently started down the path to long range shooting. I would like to know the math basics as well. However, I really will probably never use these in hunting scenarios. I would like to know the math so that I can build a program or spreadsheet. The problem that I have with all the software I have looked at so far is that you fill in variables and then it will tell you the drops. Including current zero altitude etc... What I would like to build is a program where you have a set group of variables that are locked in. For instance when I shoot a great group at the range on a certain day. I can lock in a set of variables. Then the next time I go out or I go to a different area then I can enter those variables and the program will calculate against the past go give me a good set of drops for current conditions. Without having to sero my rifle again with current conditions.

For instance. Locked variables would be Temp 60 degrees, at 1500 ft above sea level with 40% humidity etc... zeroed at 200. Then I move to 6000ft at 85 degrees and it would give me new drops without having to rezero at 200.

Is that even possible? Or would that be asking too much?

6. ### lomfs24Active Member

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Oct 25, 2009
Where do I find this program? I tried to look for it and I couldn't find it.

7. ### McTankMember

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Oct 16, 2006
Dixie Freedom,
Use a ballistic program (unless you want to loathe shooting) stay away from the math, the formula for predicting point of impact is insanely complicated and time consuming see this webpage to see what I mean Trajectory of a projectile - Wikipedia, the free encyclopedia

I use a free excel spreadsheet called "ballistic calculator enhanced sniper" Google it, it's available in different places for free. All you need to enter to get usable data is the muzzle velocity, bc, temp, altitude, scope height and range startpoint. You can enter other data, like bullet weight, wind, target velocity and range increment, if you want, but it's not needed just to obtain trajectory.

Savageman69,
As for your question "what is bullet impact height"? that's the distance on the target between your point of aim and bullet strike ie. bullet hits one inch higher than where your reticle was aimed. If you use Berger bullets use the G7 model, don't worry about decay rates leave that for chemistry. Ballistic calculators get you real close if you enter good data.