|
In a dope table, elevation is 0 at zeroing distance (50 yd) is this case. At other distances, additional angle (elevation dope) is added to the zero elevation. In other words, elevation dope is angle relative to the zero.
But we need to know the angle between the bore axis and horizontal line (launch angle / angle of departure) in order to calculate the bullet drop. We won't know that until we figure out the absolute launch angle at zeroing. Here I am taking a short cut. 50 yd is a 1st crossing zero. Assuming the gun is horizontal (fallacy #1) and negligible gravity influence on the bullet (fallacy #2), such launch angle can be estimated with the sight height. Errors happen, especially for slow moving bullet, due to the above 2 questionable assumptions. That's what I'm going to tinker next.
Here bullet drop has nothing to do with line of sight. Imagine the bore of the rifle is set horizontal and fires. The bullet drop is relative to the horizon bore axis. By principle of flat firing (launch angle much smaller than 6 degree), such drop can be estimated with the launch angle. Here lies fallacy #3, the bullet's vertical fall slows down as the speed picks up. For now I'm not going to worry about that.
It may be a bit beyond the scope of current discussion, gyroscopic stabilization of a aerodynamically unstable bullet has brought me a few more grey hairs. Bottom line is the bullet will end up with a posture (yaw and pitch) that lessens the external perturbation. A left cross wind makes bullet point to left and down, and a right cross wind makes the bullet point right and up. It lessens the effect of the cross wind by pointing into the wind. But the bullet itself keeps moving down wind. It may appear in the scope that the bullet gains on the wind. It is because of the correction angle (windage) we put in. We shoot more into the wind waiting for the wind to push right back on.
-TL
Sent from my SM-N960U using Tapatalk
|