Re: Range finder results at up and down angles.
In my opinion when evaluating exterior ballistic software a very important consideration is ease of use. If you have to type in information for 50 seconds what use is it for hunting.
At least the software should have memory which remembers the setup of you rifle. That includes scope over bore height, muzzle velocity for your loads, temperature coefficient (if known), and bullet BC for an appropriate G() model.
What else is needed?
What must be entered in the field during the shooting session? Enough info to determine air density which may be elevation, air temperature, barometric pressure, and humidity, or use an air density gage.
Then for each shot you need distance to the target (from a range finder), up/down angle to the target. Then there'd the sticky problem. How to measure wind. Pull out the Kestrel and read the direct and crosswind speed to 3 decimal places at the place you're shooting, enter the crosswind in the provided space,, set you're knobs as indicated and take the shot. It's that simple.
No it's not. For example,you're on a hill and your target is on another hill 652 yards (measured) away. It's a 14 degree down angle shot (measured) . The wind reads 5.3 mph perpendicular to your shot and it's from an angle 100 degrees from your target. But you're on the side of the hill and you're surrounded by trees.. What is the wind 100, 200, 300 and 400 yards from your location toward the target? You look though your scope and binoculars and see no mirage and no blowing plant particles. The trajectory is through clear air.
Does having a complete software ballistic model matter? Will gravitational up/down angle correction matter? How about bullet jump or spin drift effects. Those won't matter at all if the wind between 100 and 400 yards really is between 15 and 25 mph and you don't know it. So you punch in all the information 5.3 mph you have into the calculator, take the shot and miss, or worse, take a non lethal shot and the deer runs to cover before you can take another shot. You hike to the spot and spend the rest of the day trying to track a weak blood trail. Not an enjoyable way to spend a hunting trip.
Can you blame the software? Your rifle? Or your shooting skill? It can only be your fault for not realizing that wind is typically the least measurable parameter in shooting and often impossible to determine with reasonable accuracy as there may be no visible indicators. Even it you can guess or estimate the downrange wind velocity no commercial software I've seen allows you to enter downrange wind vectors for segments of the trajectory. The effect of downrange winds are likely to be much greater than up/down gravitational effects or spin drift. I don't have a solution other than to not place more faith in a ballistics computer than it deserves and choose what shots to take accordingly.
I'm not at all against the use of ballistic software, but none that I've seen put error bars on the effect of uncertainty on each of the input parameters. The book "Applied Ballistics for Long Range Shooting" by Bryan Litz (a frequent contributor to LRH) has a good discussion of how error sources combine. Even a perfect ballistic model can't do anything to correct for bad input data.
Last edited by LouBoyd; 07-25-2010 at 10:42 AM.