What does "tight eyebox" mean?
Tight eye box means a very small exit pupil.
This is NOT a bad thing for me and I'll explain.
Typical scopes & people are use to having a full sight picture with 3-4" of eye relief. Now if I were to have a scope on a 06, I wouldn't want scope bite from a quick throw up shot on a running Coyote or Groundhog. I got nailed once or twice doing that in my teens. I only shoot AG's & Bows now so no problem for me.
As a target shooter, a "tIght eyebox" helps you with repeatable hold & eye placement. I don't want a scope like this if it doubles as a pest gun. I only appreciate them as true group shooters.
Here's an example. On any scope focus it as you would for any distance on any magnification you normally would.
Now slowly move your dominant eye closer to the eyepiece. As you do this you'll see your full sight picture shrink with a black circle around it.
The lesson to be learned here is keeping the sight picture in dead center, as you pull away to get a full sight picture. Just like a round bubble level.
If you aren't comfortable with where you get the full sight picture you should adjust scope forward, or further back on the receiver. You'll also notice that this is where you would adjust the cheek piece height, the adjustable butt stock, maybe change ring height if you don't have an adjustable stock.
A anatomical stock will allow you to adjust everything for a perfect fit & feel.
The precise placement of your eye is extremely important for precise shooting. If your hold/ eye placement varies, things like parallax destroy groups and inconsistent placement shows the further you shoot.