Why align your your scopes reticle?

[imschur]

Think of it this way. Imagine sighting in your scope which is mounted at an exaggerated angle of 45 degrees to the right on a level range at 100 yards. It would work fine without issue as long as you dont change any variables. Now what happens if you move your target out to 300 yards and you adjust for elevation with the scopes elevator knob? Your bullets impact would now be several inches off to the right. Why? because the elevator isnt traveling perfectly straight up and down relative to the bore. Therefore the more elevation you dial in the farther off target you will be. All this on a flat range. Now what happens if you have to shoot up or down hill?

An easy way to test this for yourself is to take a level to the range and on a big target draw an upside down "T" that is level and square.  Aim at the intersection of where the 2 lines meet. Take a few shots and raise the elevation a few clicks and fire a few more rounds. Repeat this several times to see if your hits travel in a straight line parallel to the vertical line. If the string of hits follows a linear line in a direction away from your vertical the scope is not level to the bore.

Look at the images below for an easy understanding, but to put it simply the point of impact change will match the angle the reticle is offset from the rifles bore..

[Microgunner]

That's one thing I liked about the Shepperd scope. It has a spirit level built right into the scope visible through the ocular lens. Once you have the scope properly mounted it keeps you from canting.

[asmurff]

Thanks for the info, now today can't be a waste I learned something new.

The scope I have on my Marlin is the first scope I've ever owned. Out pure dumb luck I must have gotten it on right because when I sighted it I did horizontal  first. After I got it to the center line and started on the vertical it marched right up the center line.

Still I think I'll check it again using this method.

[techmike]

Good info - I like the "sight-in" targets that have big X-Y lines - helps to insure level reticles.

TM

[Hoss]

The scope not being parallel to the barrel, is that what we're talking here?  Or, the crossharis tilted left or right?

What is the ultimate way to mount a scope?