Depending on mount design, you'll first affix rings to base or clamp them lightly to the scope tube. Run the ring screws in finger-tight. If the rings are vertically split, heed directions as to the tightening sequence of all screws. You'll want a gap in both ring junctures when the scope is secured. It doesn't matter whether the split is vertical or horizontal; don't let ring halves contact each other.

While the scope is still loose in the rings but the lower ring or ring juncture solidly affixed to the scope base or rifle, slide the scope forward until you get proper eye relief.

Check eye relief prone and sitting, not just offhand. Wear heavy clothes as well as light. Scope position will be a compromise, but you'll want the eyepiece to clear your brow during recoil every time.

Most hunters place the scope too far back for prone or uphill shots, and the ocular ring prints a half-moon between their eyes.

As a rule of thumb, I start with the ocular lens directly over the rear guard screw--after adjusting the focusing ring for a sharp reticle image. Then I mark ring position on the tube with a pencil. It's best to leave 1/8 inch between rings and any junctures in the scope tube.

Next, turn the scope until the vertical reticle wire is lined up with your rifle's buttplate. Use a square or vertical edge or Wheeler Engineering's Level Level Level to check. If the reticle is not plumb, you will cant the rifle and miss at extended range.

Snug ring screws alternately, as you'd tighten lug nuts when changing a tire. Before finishing, see that the gaps between ring halves appear equal. These screws needn't be as tight as base screws. Over-tightening can mar and even deform a scope tube.

Bore-sight the rifle. If your mount base allows you to adjust ring position for windage, run the scope's windage dial to its center position (count clicks from one stop to the other, then come back half that number) and bore-sight using the base screws. That way, you'll keep as much windage adjustment as possible and maintain the erector assembly in the middle of the tube.

Once you've bore-sighted, it's off to the range to get your desired zero.

A careful mounting job should give you confidence in your scope. Honestly, it's rare that modern scope mounts are "knocked off" by incidental bumps in transit or on the trail.

While you're smart to check zero in camp after extended travel, you shouldn't find any change. Just remember to fire a three-shot group before pulling turret caps and fiddling with the zero.