an old gunmaker told me 40 years ago.When you site in at 25 yards adjust scope to 1 inch low at 25 yards,puts you on at 100.Because the bullet is rising when it leaves the barrel and will continue to rise for x amount of yards.Seems to have worked.
Boresight, two lines that never meet
- Thread starter Redleg
- Start date
The article says you can EITHER use a ballistics calculator or use trigonometry to calculate the departure angle.
I've never used a ballistics program or app on my own computers, so I'd just assume that it does the math based on angles and distances, not bullet velocities and trajectories.
I don't see the word "parallel" anywhere in that article, and although the drawing of the rifle makes it look the the scope is parallel to the gun barrel, the lines he drew to show the bore axis and line-of-sight have them as straight lines, not parallel, but intersecting, forming a triangle (actually, a right triangle) with a small rise leg, a long run leg, and a slightly-longer hypotenuse.
The drawing and accompanying text are correct that if the rifle barrel is what's parallel to the ground, perfectly level, the scope (at least its internal lenses and reticle) must be tipped downward to meet the bore axis that started its path from a couple inches below the scope.
For close-range shooting you can do that.
For longer range shooting with significant bullet drop, you'd have to elevate the gun barrel. The scope's line of sight might be perfectly horizontal, or not, but it would surely be closer to horizontal than the gun barrel, which would be tipped upward measurably.
I've never used a ballistics program or app on my own computers, so I'd just assume that it does the math based on angles and distances, not bullet velocities and trajectories.
I don't see the word "parallel" anywhere in that article, and although the drawing of the rifle makes it look the the scope is parallel to the gun barrel, the lines he drew to show the bore axis and line-of-sight have them as straight lines, not parallel, but intersecting, forming a triangle (actually, a right triangle) with a small rise leg, a long run leg, and a slightly-longer hypotenuse.
The drawing and accompanying text are correct that if the rifle barrel is what's parallel to the ground, perfectly level, the scope (at least its internal lenses and reticle) must be tipped downward to meet the bore axis that started its path from a couple inches below the scope.
For close-range shooting you can do that.
For longer range shooting with significant bullet drop, you'd have to elevate the gun barrel. The scope's line of sight might be perfectly horizontal, or not, but it would surely be closer to horizontal than the gun barrel, which would be tipped upward measurably.
Bullets don't travel above the barrel line. If you were to shoot any rifle with the barrel perfectly level to earth the bullets begins to drop the second it leaves the barrel. In order to hit a target at any distance you have to point the barrel upwards, hence the trajectory and two different zero's.
Oh lord, this picture from the article
that's not how it works, that's not how any of this works.
GAgun, I agree with your 3rd comment, the barrel is parallel making the line of bore parallel to the line of sight. Then you have to have a line of displacement that represents the adjustment that is made to the sight setting to get it the crosshairs on the target that you can see through the bore, so the article is good for thought, but the triangle is misleading, the 90 degrees angle is formed from the line of bore long leg, distance between line of sight and line of bore short leg and the slightly-longer hypotenuse sloping downward instead of upwards.
This diagram might help. The one in the OP is misleading and will just screw with your head.
Biker13, good advise, ran the numbers with 30-06 and it gave me good data within five inches of point of aim out to 240 yards.
If'n you jerk the trigger like I do, ain't no fancy triggernometry calculations gonna help!
That hilarious.View attachment 1470566
Oh lord, this picture from the article
