Hi Brown Bear,
The basic thing about sighting in a rifle is that any round ball or bullet will not travel very far in a straight line. As the fps bleeds off the bullet drops. If you've ever thrown a rock, you know how this works. If you throw it straight, it goes straight for a short while and then drops down. If you want to throw it farther, you throw it up in the air more to give it the trajectory to reach that farther target.
You are doing the exact same thing with your rifle although it happens at a much higher speed and the arc isn't nearly as large.
So, when I sighted in my .50 cal shooting a .490 patched round ball at 1800 fps (feet per second) to hit dead on the spot I was aiming at 100 yards, the round ball follows an arch that takes it 2" above my point of aim at 50-yards, hits dead on at 100-yards and drops 2" below my point of aim at 115-yards. Beyond that distance, the round ball drops quickly as the speed bleeds off.
That trajectory is a basic premise of ballistics. So, to get a rifle to hit the point of aim at 100 yards, the ball has to travel in a slight arch that is about 2" higher than aimed at 50-yards. If the rifle were not sighted in to do that, but was fired in a straight plane, it could hit the 50-yard target dead on but would drop so much by the time it went 100-yards that it would be hitting 4 to 5 feet below the point of aim. So if it shoots a little high at the mid point, it will hit my point of aim at the distance I sight it in for...in this case 100-yards.
With the arc that the round ball travels to do this, I will shoot a little low at 25-yards, 2" high at 50-yards, about an inch high at 75-yards and spot on at 100 yards. So, if I do my part, I will always hit within 2" of where I'm aiming out to 115 yards. That's more than accurate enough to kill deer.
Does that help?
Twisted_1in66 :thumbsup:
The basic thing about sighting in a rifle is that any round ball or bullet will not travel very far in a straight line. As the fps bleeds off the bullet drops. If you've ever thrown a rock, you know how this works. If you throw it straight, it goes straight for a short while and then drops down. If you want to throw it farther, you throw it up in the air more to give it the trajectory to reach that farther target.
You are doing the exact same thing with your rifle although it happens at a much higher speed and the arc isn't nearly as large.
So, when I sighted in my .50 cal shooting a .490 patched round ball at 1800 fps (feet per second) to hit dead on the spot I was aiming at 100 yards, the round ball follows an arch that takes it 2" above my point of aim at 50-yards, hits dead on at 100-yards and drops 2" below my point of aim at 115-yards. Beyond that distance, the round ball drops quickly as the speed bleeds off.
That trajectory is a basic premise of ballistics. So, to get a rifle to hit the point of aim at 100 yards, the ball has to travel in a slight arch that is about 2" higher than aimed at 50-yards. If the rifle were not sighted in to do that, but was fired in a straight plane, it could hit the 50-yard target dead on but would drop so much by the time it went 100-yards that it would be hitting 4 to 5 feet below the point of aim. So if it shoots a little high at the mid point, it will hit my point of aim at the distance I sight it in for...in this case 100-yards.
With the arc that the round ball travels to do this, I will shoot a little low at 25-yards, 2" high at 50-yards, about an inch high at 75-yards and spot on at 100 yards. So, if I do my part, I will always hit within 2" of where I'm aiming out to 115 yards. That's more than accurate enough to kill deer.
Does that help?
Twisted_1in66 :thumbsup:
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