The fellow that taught me how to shoot was a Korean war vet. He used to tell me that the 25 yard zero was what the army taught him, but he said that he learned that about an inch or two low was better IF you had to do this in a pinch.
I have had several loads which didn't go where they were supposed to downrange after 100 yard sight in. In most cases, the drop wasn't as much as I expected according to drop tables.
They weren't real far off...but I wonder; are the computer programs accurate? Is there a case to be made that the bc may not be correct?
Bill
BC is dependent upon a variety of external factors; thus, it is not truly a constant. This is one reason that (when you could still buy them) Oehler's PBL used an acoustic-type device to aid in measuring the BC at the target. In the absence of the ability to measure BC, you can try determining bullet path at several different distances (the greater the number and the farther out, the better), then forcing your ballistic software to match the trajectory over the measured distances.
If you have enough data points and can shoot out to 400 or 500 yards, you don't really need ballistics software--a simple plotting program with the ability to fit data to two or three orders will suffice. They are free and on-line. I can highly recommend the Wolfram Alpha site. The interpolated results will be quite exact and the extrapolated results will yield more accurate results than if assuming a standard BC. You can then try this experiment again at different times of the year. Depending upon the weather and your location, you will see some variability, particularly at longer ranges.
