Just For Fun - Ballistic Calculator Comparison

[Semisane]

I've been using an on-line ballistic calculator on the Handloads.com web site (http://www.handloads.com/calc/) andgot to wondering how it compared to the Barnescalculator Sabotloader uses. So I captured one of his from another post and plugged the same figures (velocity, bullet weight, BC, etc.) into the one I've been using. Both of them are shown below. They don't agree exactly, but arepretty close together.

[gleason.chapman]

This is a Screencast of how to use a Ballistics Program, here are the steps:

1) get the ballistics coefficient of the bullet
2) you know the bullet weight
3) determine the sight in range (usually dead on at 100, 2" high at 100, 3" high at 100 or for elk 4" high at 100)
4) drop your values into the calculator

here is a Screencast (i.e. a video) of how to do it:

http://screencast.com/t/lMfVKhXe

Here is the result:



You can use the free copy of Jing to do your own screencastsby downloading itfrom www.jingproject.com. Excellent simple tool for showing a sequence of steps with audio.

Chap

[Underclocked]

Maybe the 5mph crossing wind creates the difference in calculations?

[Semisane]

Maybe the 5mph crossing wind creates the difference in calculations?

I hadn't thought about that. But I just ran the calculator again with 0 wind and the velocities and drop did not change. Adding a cross wind in just gives you a figure for drift. Actually, I was a little surprised at how close togetherthe two calculators were.

[Underclocked]

oops.

I really don't know what you guys are talking about.

[Semisane]

Just goes to show you that you can read the charts anddata from the bullet and powder manufacturersto get yourself in the ball game, but you really don't know what it's going to dountil you actually shoot the bullet/powder at different ranges.

[driftrider]

Underclocked,

You values may show different because you set it up for a 200 yard zero. The other charts used a 145 yard zero to achieve MPBR. Though the total drop is different, and that isn't dependent on the range of the zero. I think that it's just a slight difference in the drag models used by the various ballistics algorithms.

Just for s**ts and giggles, I punched the data into both the ballistics calculators I have on my Palm, and go the following result for the 200 yard drop:

Program A: .-9.74", 29.17" total drop, TOF 0.42 seconds. It also calculates the max ordinate of 3.20" at 85 yards, and the bullet reaches -2.98" at 167 yards.

Program B (which is remarkably similar to ExBal): If you use the "Solve Zero Ranges" function, which calculates the optimum near and far zeros for MPBR, you get a near zero of 16 yards, far zero of 143 yards, max ordinate is at 83 yards, and the MPBR is 166 yards. The mil-dot range solver shows that, with a 145 yard zero, and all the other parameters, the output shows the drop as -9.06" below LOS, with a wind drift (5mph, 90deg) of 8.24".

All pretty close, but no right one exact. However, the differences aren't so great that any of them, assuming one version is accurate, would cause a miss on a deer sized target at 200 yards.

Mike