m = <y/ over <x

<y is the change in variable y
<x is the change in variable x

Slope is used to find the relationship between two variables.

Example: temperature and muzzle velocity.

We all know that changes in temperature will affect muzzle velocity, which will affect bullet drop.

Use: say you are testing ammunition to find how the MV is affected.

For example at 20-degrees F your load produces 2600fps
at 120-degrees F your load produces 2650fps.

Finding: a 100-degree increase in temperature produces a 50fps increase in MV. Slope = 50fps/100-degrees, = 0.5fps per degree temperature increase.

Result: you can now estimate the MV for any temperature.

MV = 2600fps + (45 minus 20)times 0.5-degrees. 25-degrees times .5fps per degree increase.

MV = 2612.5fps.

Pertinent usage: if you are a hardcore Rockchuck shooter at extended ranges (like how far away you can range them with your GEOVIDS).

If you establish a zero at 100 yards, you might make good use of a ballistics program to figure drop, in the click values your scope has.

That drop chart is not field useful if the temperature changes by 20 or more degrees. I start shooting at daylight. Maybe 60-degrees. Four hours later, temp is up 30-degrees.

If you load the FREE ballistics calculator from Brian Litz onto your smart phone, or splurge and get a Kestrel wind gauge with it already installed from Applied Ballistics (Litz' company)

you can enter the change in temperature and have the machine recalculate your drop in inches or click values.

Doesn't sound like a lot, but if your Rockchuck standing out there at 600+ yards and you do not correct the setting on your scope you will miss him/her every time. EVERY TIME!!

I have this nifty new scope that allows me to zero at 100 yards, and then loosen two itty-bitty setscrews and reset the scope turret to absolute bottom, then retighten them. I can get the program to tell me how many clicks to go up to hit my target at any yardage my load will reach at supersonic speeds.

I am not getting into the Transonic area, the bullet's flight path gets unstable, and non-quantifiable from Mach 1.2 to Mach .8.

Only trouble is station temp changes air density, so it is not a one line equation.

US Army Sniper manual tells us that with M118 special ball, 20 deg F change in temp equates to a 1 MOA poi shift, 20% change in RH does the same, 1000 ft in altitude ditto- so now not only does the air temp matter, but it can be offset by RH or alt or both or neither....

I doubt that a 50 fps change in MV due to a high temp condition will offset a 1 or more MOA change due to air pressure.

Welcome to the mathematical portion of shooting at range.

That's why I have the Applied Ballistics Software on my Ipad and the incoming Kestrel tools.

I'm still learning, much of this is fairly new to me.

My home range is at 2400+/- feet above sea level. Where I shoot most of my chucks is about 4500 to 7000 feet above. I make it a point to rezero when I get there; and re-enter the data.

My Big Gun will be here Wednesday, the OM 70 is at Bartlein's waiting for the tightneck 6.5-284 reamer from JGS to get there.

Did I mention that it has a Kenyon trigger? Yessssssssss...

Yes, but thanks for reminding me.

quote:

Originally posted by Idaho Sharpshooter:
That's why I have the Applied Ballistics Software on my Ipad and the incoming Kestrel tools.

I'm still learning, much of this is fairly new to me.

My home range is at 2400+/- feet above sea level. Where I shoot most of my chucks is about 4500 to 7000 feet above. I make it a point to rezero when I get there; and re-enter the data.

My Big Gun will be here Wednesday, the OM 70 is at Bartlein's waiting for the tightneck 6.5-284 reamer from JGS to get there.

Did I mention that it has a Kenyon trigger? Yessssssssss...

there is nothing free about it! On their website link, the apple store and the Android store it is all the same price; $29.95!

quote:

If you load the FREE ballistics calculator from Brian Litz onto your smart phone, or splurge and get a Kestrel wind gauge with it already installed from Applied Ballistics (Litz' company)

You have to start at www.bergerbullets.com

header row, on the right: Ballistics Calculator.

Click on that and enter your data. If you can access the internet on your phone, you can do this.

Yes Rich I know how to access the net on my phone. If you recall I am the one that showed you how to retrieve the many voicemail's you did not know how to get as well as many of the other features you still do not know how to use.

That said...
The only ballistics program I can find on Berger's site,for free, is the basic one almost all of the bullet makers have available and I have used many times.

There is a link for the Applied Ballistics version and it is just shy of $30. I am sure it is well worth it.
this is the link for the one you have to pay for

http://www.bergerbullets.com/bryan-litz/



this is the free one
http://bergerbullets.com/ballistics/

I and yes I can get all this info from my phone

I meant that you can download and print out the individual ballistics charts.

should of said that then or at least something close to that. oh well

got my hopes and dashed them. I guess I will go play with my phone instead.....