If you have a rifle set up and intended for home-defense, how should you zero the red dot sight for home-defense distances? Rob Pincus has an Aimpoint Comp ML3 mounted on his rifle. It has a 2 MOA (minute of angle) red dot, meaning it’s a fairly small dot. It will be capable of a significant amount of precision.
Zeroing the Red Dot
Where are you going to zero the red dot? The red dot, the line of that optical line, is only going to cross the line of the bore once, for practical purposes. For a defensive rifle, we’re not worried about the arc of the bullet and the fact that the path is going to be crossed twice in space. We’re concerned with what’s going to happen close in. Think about the distances you’re likely to use this rifle at: probably inside-the-home distances as this is one of your home defense weapons.
As with all rifle training, we prepare not only for the most likely scenario, but also for other plausible scenarios. You may use the rifle around a vehicle or defend a family member outside your house, and you’ll extend the distance out to 20 or even 50 yards.
For that reason, we don’t want to crank the optical line so tightly to the bore that we zero the red dot at that very close distance. We want to make sure we’re a little bit offset. The way to get a proper offset for a home-defense rifle is set it for a distance at 50, 75 or 100 yards as your practical zero. This will give you that offset inside your home.
Adjusting the Red Dot
Fire a couple of rounds to see where they impact and how much the red dot needs to be adjusted. After taking the caps off, adjust the red dot by using an empty piece of brass. Fire another round to see if you have adjusted the red dot enough.