sight height

[solst_ice]

Just for the sake of interest, how is the sight height measured correctly?

JBM defines the sight height as:

The height of the sight (or scope) above or below from the centerline of the barrel.

Till now, I measured it from the center of the bore to the center (radius) of the objective of the scope.
Some thoughts:

1) What if the scope is mounted in a tapered scope base, e.g. 40 moa? T


Let's say our rifle is setup with non-tapered scope base and the line of sight and the bore axis are parallel. We can measure the sight height from the center of the bore to the center (radius) of the objective of the scope.

Now let's assume, we will replace the 0 moa scope base with a 40 moa tapered scope base. When the elevation is not changed, the bore axis and the line of sight will not be parallel anymore.


2) Should the sight height now be measured, or better calculated, at the muzzle? Means, the distance from the reticle to the muzzle and also the angle of the line of sight do have an influence, or? In this case, the line of sight will be less than we were using the non-tapered base.

3) Doesn't the position of the reticle also have an influence?


I know, it will not effect the ballistic calculation that much. But that stupid question doesn't leave me alone.

 

[Deleted member 113831]

The point of convergence within the scope that actually changes the sight angle is the plane that contains the reticle. That point is more or less right under the turrets.

 

[Sig Marine]

Most measure from the action’s pressure relief hole to where the top and bottom of the front scope ring meet which is the center of the scope tube.

 

[SubOptimal]

I usually go from the center of the windage turret to the center of the bore. You can OCD this stuff if you want but a calibrated eyeball brings me close enough. I may or may not refine data later depending on what my POI looks like at various distances but comparing 100 and 500 data to what my solver gives me, provided all the other crap in there is right, I'm usually within 0.1 mil or so.

 

[Rob01]

I measure like this. Has worked great for 15 years so sticking with it. Takes about 2 seconds and no math. Plenty accurate for ballistic programs. Center of bore to center of windage knob. Doesn't matter if MOA base or not.

 

[Bigwheels]

For those as A-R as I am. I would think that you measure @ the objective since that is the 1st lense the light goes through into the scope. Inside the scope the light will be bent through multiple lenses before getting to your eye.
But I could be wrong...
Either way I've run numbers in several solvers & a .2" change in height seldom even makes 1 click difference @ a mile.