Quote:
"actual testing at range will often illustrate that the ballistic calculators are not a reliable estimator of trajectory."
I have found just the opposite. The ballistics programs are excellent trajectory predictors, at least all of the ones I have owned. The secret is to not use the default settings. To have them accurate you must plug in all the actual values for things like:
scope height, measured muzzle velocity, altitude(very important), temperature, barometric pressure, humidity, etc.
Even at 1000 yards every program I have ever tried has been within 1 MOA, usually less.
Jack
Oh, I agree that if all is entered the results are usually pretty close. An example of where it is not reliable is the "scope height" setting. The flaw here is the distance of the objective lense from the muzzle.
Even more flawed is the use of iron sights where the correct procedure is to measure the height of the front sight, but that does not take into account the sight radius from front sight to rear aperture. This is a source of major differences but you must actually lay those out on paper to see them. While you can change the scope height entry you cannot make any entry to account for the angle of view from objective lens to line of bore or for the angle between the front and rear sight as it compares to the line of the bore.
Like you said, altitude is very important and given our original questioners load data, it could make a difference of almost 200 inches at 1000 yards between 500' and 10,000 feet. Just another reason why the calculators are not that practical in the field unless you are shooting paper with all the local factors known.