Where to mount scope on AR?

[1Luv4SF]

I would like to know how far down my rail I should mount my scope on my AR15. Its a 4-16x 42mm scope. Ive tried mounting it in different spots and cant seem to find the "sweet spot". If my MOE stock is fully extended, how far from the end of the stock to the back of the scope should it measure roughly?

[Rock6.3]

This is a personal measurement for two reasons:

1. What is the eye relief of your specific scope at the magnification you use it at?
2. How long is your neck (and thus your proper cheek rest position on the stock)?

This combination of factors tells you what you want to know.

My method:
1. Get a helper and provide them a measuring tape.
2. Get into position with your cheek firmly planted in your normal shooting position.
3. Have the helper measure from your charging handle to approximately the front of your eye.

Subtract item #3 from the eye relief of your scope.
Mount the rear of your scope that many inches in front of your charging handle.