The Firing Line Forums - View Single Post - 100 yard 0 and -2.5” at 10 yards?

HiBC · December 23, 2018, 03:48 PM

Draw a picture. Draw one straight line to represent the line your sights work with.Your scope is above the bore centerline a distance,perhaps 2 in.That varies with ring height. That line is straight.

Now you need to consider another line. The axis of the bore.Its straight,too.You scope knobs let you adjust the axis of the line of sight.We adjust the axis of the line of sight and the axis of the bore so they cross at a fairly close range.This range will vary with sight height and the desired sight in distance. Typically,it might be 25 to 40 yds,just to give you an idea

The bullet exits the bore following the axis of the bore. There is a fine point to grasp here.As soon as the bullet leaves the bore,gravity begins to accelerate it towards earth at an acceleration of approx. 16 fps per second ,assuming horizontal flight.

Technically,the bullet never "rises" But the upslope of the bore axis tosses the bullet up through the line of sight,and they cross twice.Once at the approx. 25 to 40 yd place,then for a while the bullet is above the line of sight. This is described as "mid range trajectory" You will see that term again. The bullet reaches a max midrange trajectory,then gravity begins to pull it down. The bullet crosses the line of sight again.That is your sighted in range. Beyond that,the bullet path will be below the line of sight as it accelerates toward earth.

With your high vel cartridge,try a 40 or 50 yd target. If you are sighted in at 100 yds,there will be an intermediate range where you are dead on.

Remember that range.It will be useful for future sight ins

I don't know what part of a deer you aim at, but I think you might not be looking at the correct reason you missed.

Actually measure your sight height.Like,1/2 the scope tube dia,plus 1/2 the receiver dia,plus the space between the receiver and the scope tube(or another method)

For a low mounted hunting scope,thats often 1 1/2 in.If you have a high mounted scope,it will be a bit more.

That distance is the MAX you could have "missed" Even if that's 2 in,you must be shooting at the edge of the deer.

But,at someplace betwee 25 and 40 yds,or thereabouts,the line of site vs line of bore would be very close. I doubt you had even 1 inch of error per your theory.Should be eating venison.

Do more checking to verify,but I strongly suspect you missed for another cause.

December 23, 2018, 03:48 PM	#2
HiBC Senior Member Join Date: November 13, 2006 Posts: 8,287	Draw a picture. Draw one straight line to represent the line your sights work with.Your scope is above the bore centerline a distance,perhaps 2 in.That varies with ring height. That line is straight. Now you need to consider another line. The axis of the bore.Its straight,too.You scope knobs let you adjust the axis of the line of sight.We adjust the axis of the line of sight and the axis of the bore so they cross at a fairly close range.This range will vary with sight height and the desired sight in distance. Typically,it might be 25 to 40 yds,just to give you an idea The bullet exits the bore following the axis of the bore. There is a fine point to grasp here.As soon as the bullet leaves the bore,gravity begins to accelerate it towards earth at an acceleration of approx. 16 fps per second ,assuming horizontal flight. Technically,the bullet never "rises" But the upslope of the bore axis tosses the bullet up through the line of sight,and they cross twice.Once at the approx. 25 to 40 yd place,then for a while the bullet is above the line of sight. This is described as "mid range trajectory" You will see that term again. The bullet reaches a max midrange trajectory,then gravity begins to pull it down. The bullet crosses the line of sight again.That is your sighted in range. Beyond that,the bullet path will be below the line of sight as it accelerates toward earth. With your high vel cartridge,try a 40 or 50 yd target. If you are sighted in at 100 yds,there will be an intermediate range where you are dead on. Remember that range.It will be useful for future sight ins I don't know what part of a deer you aim at, but I think you might not be looking at the correct reason you missed. Actually measure your sight height.Like,1/2 the scope tube dia,plus 1/2 the receiver dia,plus the space between the receiver and the scope tube(or another method) For a low mounted hunting scope,thats often 1 1/2 in.If you have a high mounted scope,it will be a bit more. That distance is the MAX you could have "missed" Even if that's 2 in,you must be shooting at the edge of the deer. But,at someplace betwee 25 and 40 yds,or thereabouts,the line of site vs line of bore would be very close. I doubt you had even 1 inch of error per your theory.Should be eating venison. Do more checking to verify,but I strongly suspect you missed for another cause. Last edited by HiBC; December 23, 2018 at 04:03 PM.