Looking for the math

[LR1955]

Wasn't sure how else to put this...

While I wait for payday to order the next part of my Grendel build I have been trying to further educate myself on the more interesting side of long range target shooting. A handful of Google searches has shown me several good online and app based calculators. But very little information on what goes on underneath the GUI.

So far, what I have gathered is that I should know:
Optic height, as measure from center of bore to center of optic
Projectile weight
Muzzle velocity
Bullet trajectory
Barometric pressure
Temperature
Elevation
Elevation difference between target and muzzle
Humidity
Wind speed
Wind direction
Powder burn rate
Barrel length
Rifling twist rate
Number of rifling grooves
Wind direction

Am I missing something?

So, my question is, how do I use this information, if I want to hand jam it?

I have the rifleman's rule. But beyond that I'm at a loss. Either I am not searching the proper terms to find it, maybe I have accidentally skipped over where the information is stored, or the entire internet is conspiring against my love of math.
First two seem more likely.

I was hoping to do this without spending money on a book at this point. All my spending money is going into rifle parts and reloading supplies at this point. Once I have it built I may collect a shooting library. But for the now I am trying for the free education.

I understand how the majority of this information will affect performance. A few things I am iffy on:

Would powder burn rate be a direct affect on muzzle velocity, and thus not be needed as additional information?

I understand twist rate, but how does number of grooves affect point of impact calculations? I saw more than a few calculators ask for this information. Usually followed up with groove depth(if known) or something like that.

Wouldn't elevation difference be covered by rifleman's rule, or am I missing something?


I realize I am repeating some things which have most certainly been previously covered in this subforum, so I apologize for that.

Here is how you use this information to get a ballistic solution (elevation for a distance). Providing of course this is what you are after. Not really sure after I read your listing.

Ballistic Coefficient (G-7 if possible).

Muzzle Velocity.

Bullet Weight.

Altitude if you are above about 3000 feet.

Sight height above center of bore.

Plug into a simple ballistics calculator and you should come up with solutions that are quite good to the subsonic range of the load.

However, a few things you forgot that must be quantified in order to understand hit probabilities.

1. Mean radius of the ammunition so you can extrapolate Mean Radius at a distance.

2. Hit and Kill zones of target.

3. Probability that the shooter is able to hold well enough, estimate wind well enough, and pull trigger well enough for his shot to maximize the probability of hit / kill of his ammunition against a specific target at a specific range given specific environmental conditions. For this you will have to deal mostly with physical and psychological stress on the shooter.

Most of your variables, if they have significance, pale when considering the capability of a shooter to make a shot.

LR55