[eflatminor]

I was set to buy a ballistics computer program from either Seirra or Barnes when a fellow shooter at the range mentioned a program he liked better called X Ball. Trouble is, I can't seem to find any reference to X Ball on line. Does anyone know of this program? I'd love to hear your thoughts and/or a link would be great.

Thanks!

[RyanM]

Is this an internal, external, or terminal ballistics program you were looking for?

Internal, about your only real choices are Load From a Disk ($65), and QuickLOAD ($150).

External, there are about a million and a half totally free programs you can use. Just do a search for "external ballistics calculator."

Terminal, I've got a calculator (in spreadsheet form) I'm programming myself. I'd say it's a late alpha build right now, but I can send you a copy if you want.

[eflatminor]

I hadn't thought about those distintions but of course that makes sense. You're suggesting all the external programs are alike. That too makes sense because the math is the math. Perhpas the fellow suggesting "X-Ball" liked it for some other reason such as input variables or the 'look and feel' of the program? I don't know, but thanks for the heads up about the free programs. I'll give them a try.

I'm a bit ignorant about terminal ballistics. Can you say what your spread sheet will calculate, how it will be used, etc.

[RyanM]

Well, actually, there are several different equations that can be used for external ballistics, I think about a dozen. I haven't tinkered with them that much (I mostly shoot pistols, so extreme long range trajectory isn't much of a concern for me), but I think the equations are supposed to represent different bullet shapes, or something like that. One of the main differences I've noticed between the free and the money-cost external ballistics programs is that the free ones are usually much simpler. I think I saw a rather expensive program once which actually had a database of thousands of bullets from different manufacturers, so you wouldn't need to input that stuff yourself. It would also take into account the fact that the BC changes with velocity.

Still, for most purposes, a simple free calculator will get you within spitting distance.

For terminal ballistics, my calculator will basically tell you how big of a hole you can expect a bullet to make, given a ton of input variables telling how the bullet performs. For instance, let's say you wanted to know how well a particular .308 load would perform. You'd have to start by seeing how the bullet performs.

Easiest way to do that would be to line up about 8 or 10 one gallon jugs of water and shoot them, at whatever distance you think is most likely. Recover the bullet and as many fragments as you can, and take them home and measure them. For recovered diameter, you want to measure across the bullet 6-8 times, evenly spaced around the bullet, and average them. Recovered weight, just let it dry out and throw it on the scale. That should be enough for the calculator.

So let's say it was a .308, 150 gr softpoint at 2750 fps, expanded diameter 0.65", recovered weight 103 gr, impact velocity 2500 fps. Jacket stayed on, and the fragments were about birdshot-sized, not tiny specks of lead, or gigantic chunks.

You'd input:

caliber: 0.308"
weight: 150 gr
impact velocity: 2500 fps
recovered diameter: 0.65"
recovered weight: 103 gr
fragment effectiveness: 100% (default value; shedding jacket or having fragments that are really big or really small decrease this)
coefficient of drag constant, before and after expansion: 0.40, 0.68 (you use a reference table to find the values for this and the next two)
penetration threshold velocity, before and after expansion: 10, 50
constant #5, before and after expansion: 50, 35
target thickness: 12" (about how wide what you're shooting at is; 12" would be a big deer)
skin thickness: 0.20" (I think that's about how thick a deer's skin is, anyway)
body weight: 200 lbs

Then the calculator would tell you:

maximum penetration: 15.1"
exit velocity: 0 fps (doesn't exit with given target thickness, 12" in this case, so it would penetrate 12" out of the possible 15.1", and stop just under the skin)
average hole diameter: 3.046"
maximum hole diameter: 4.722"
mass of tissue destroyed: 1326.43 grams (nearly 2 pounds, 15 ounces)

[xtarheel]

One of the best external balistics programs that I have used is actually free on the internet. It is called Point Blank and can be downloaded at www.huntingnut.com It has a data base of bullets and primers; calculates point blank ranges, saves your reloading data, and has a utility to catalog your firearms, plus many other neat features such as alowing you to print out a target and then enter and save your shot placement. Worth a look. I like it.

[Zak Smith]

The program's name is "exbal", ie, "external ballistics."

[eflatminor]

Zak, thanks so much. Your post was a "Duh!" moment for me. I've place an order for Exbal and will report back once I've gotten the hang of it.