Long range first hit mathematical forumulas

[Marine sniper]

When I taught marksmanship and ballistics at 1st. Marine Division Scout Sniper school, one of my main concerns was the students ability to predict where a bullet would impact on the first shot. Obviously a sniper does not want to have to shoot spotters in order to effectively engage a target.

I was wondering what are some of the formulas the hunters here use to help them predict the cold bore shot at an unknown distance, at elevation, in the wind, at an angle, etc.

What if you are at 1000 feet more elevation than what you sighted your gun in at? and you are shooting up hill at 12 degrees? there is a 5 mph wind from 10 to 4, etc. You laz the target at 945, you have dope for 900 and 1000, but that was on level ground at 1000 feet les elevation, etc.???? What do you do. Or do most of the hunters here make an educated guess and hope his spotters sees where he hits?

I will jump in with some of my experiences if the thread takes off.

John

 

[Guest]

John,

Now this could be some good stuff

ok me personally.. A-trag program and load data sheets
assisted by the COS angle indicator X distance ( for up hill down hill)

I personally don't have a formula for 1000-10,000 ft elevation changes... seeing as I live out west and I know what my rifles do at elevation and when I go back east to hunt shots are all under 200 yards...

 

[bailey1474]

My method doesn't require much skill or know how. I just punch the numbers into exbal on my palm and dial the scope!!

I have no doubt that I can hit a man sized target on the first shot out to 1000 yds w/this program.

 

[ss7mm]

Marine sniper:

Pretty much like the others. Exbal software running on a Palm in conjunction with a Kestrel 3500 meter for all of the weather type stuff, ACI for any angles and a Swarovski range finder.

Range it, check the weather related data, read wind conditions where possible, check the angles, input all data into Exbal and my brain, dial scope, pull trigger.

It's actually faster than it sounds because a lot of the data gets put in as soon as I get out of the truck.

 

[704]

Calll in Artillery.

Just kidding.

 

[Eaglet]

I do the same as Ric Horst, Exbal saves the original sighting in information, including temp.,Bar. Pre.,Altitude,Humidity. When we move to a different place, higher Elevation and all the other stuff, we input that new info in Exbal and using the two sets of info Exbal will give us the numbers to dial for elevation and Windage. The slope angle as well as everything else will be included in the new set of settings for the turrets.

 

[Eaglet]

Marine Exniper,
I'm pretty sure you have knowledge and experiences that would help us all, so... come on!

 

[davewilson]

i'm pretty new to this and go by my drop chart for distance.altitude is not a variable for me here in Pa. but i allow 1/4 moa for every 10 deg difference from my sight in temperature.

 

[Marine sniper]

I remember when I taught at Sniper school I used to think "I dread the day computers are used to do all the calculations we do now with a calculator, formulas, and expericance." Unfortunately it appears those days have come. No offence to anyone using Exbal, but we used to spend months on the range honing our skills to do what these little handheld programs will do. I have not used Exbal yet, but will. It is the end of an art.

The main problem we had back in the early 90's was accurate range estimation. If you know the size of the target mil-dots can be very accurate. Next was up hill down hill range estimation (and shooting), using mil-dots as the range estimation tool. We figured out if you took a vertical mil reading and multiplied it by the cosign twice it was accurate.

For windage we had a formula that was range x wind velocity x value of the wind in % divided by the constant for that range. The constant changed with each 25 yards in distance.

We shot at 10 in. wide moving targets (walking speed) out to 600 yards with a .308 Winchester. We used the spaces between the mil-dots to figure the lead. Most guys shot a one mil lead on a walking speed target to hit dead center at 600 yards (approx 26 in. lead)

We had a lot of other formulas that I am looking forward to testing against the computer.

We also did a lot of cold bore shot documentation. To cut to the chase; what we discovered was the higher quality barrels produced more accurate cold bore shots. A sniper rifle can not be effective if you have to shoot it a few times before the groups settle down and get accurate. With the real good barrels the cleaner the barrel the more often the cold bore shot was right in the middle of the group. For the lower quality barrels we found that by doing a lot of experimentation with cleaning procedures you could usually find a cleaning condition (i.e less than totally clean) that the barrel liked enough to produce a reasonably accurate cold bore shot.

There is more; but I am tired and going to bed

John

 

[Eaglet]

Verry impressive, long range shooting really took some kowledge, I do remember the days when the first scientific calculators came out and at school they still wanted us to use the trigonometric tables. You're right that's in the past but in itself it was art. Too easy now, but I have to admit it's a lot of fun! /ubbthreads/images/graemlins/smile.gif

 

[ricka0]

Re: Long range first hit mathematical formulas

One thing we can probably all agree on is that BDC are bogus for long range one shot kills. Good for TV tho I just got my 2nd ACI today - what a great product.
Humidity is not worth entering - it's noise.
Great info. I'm going to have to pay more attention to my first shot. If you want to know your first shot I'm guessing you <ul type="square"> [*]Clean barrel between each shoot [*]Let the Barrel cool to ??? between shots [/list]

 

[Eaglet]

Re: Long range first hit mathematical formulas

b1g_b0re,
I've got to get me one, the A.C.I. I mean. I just don't want to mount it on my scope and do not have the right base to do different. If I told you what I use for shooting at different angles you'd be laughing the rest of the weekend. /ubbthreads/images/graemlins/smile.gif

 

[Guest]

Re: Long range first hit mathematical formulas

I have the ACI on the WM and the 308... invaluable tool when shooting in the hills out here...

BB... I never shoot from a clean barrel! If you know you are going to shoot your rifel within a few weeks leaving you barrel "dirty" won't really hurt it.. If I know I won't be shooting that rifle for a while I put her away clean...

after a range session.. I'll clean real good... then before I put the rifle up.. I'll fire a shot at 100 yards if I hit the bull I put her away if shes a bit off I'll fire one more...after about 5-10 mins to make sure the barrel is cold... typically I'm right in the middle.. then I put her away.
Since most of the groups you collect data on tend to be 5 shot groups or more they are dirty barrel groups. It makes no snese to go out shooting or hunting with a cold clean barrel... so I usually go out with a cold dirty barrel.

 

[Guest]

Re: Long range first hit mathematical formulas

BB question....

out here humidity deosn't play in as a factor we are dry as a bone..
I am wondering though....lets say we take our rifles to Alabama and humidity is 95% I think it would affect the trajectory.. no?