Shooting rifles for as long as I have has taught me to appreciate the importance of precision. And it all starts with understanding 4 inches for zeroing.

Minimum Level of Accuracy

If you shoot long enough at some point the subject of “minute of angle” comes up. If you don’t have a good feeling about MOA then do yourself a favor and watch the video in the attached link. MOA is an angular unit of measure. In its simplest form it is expressed as 1MOA equals 1 inch at 100 yards. So, 4 inches would be 4MOA. That is the minimum level of accuracy necessary to correctly and accurately zero any optics or sights for rifles. Now, this can get really complicated really fast when you consider all the variables. But let’s zoom in and focus on pistols with red dot sights. Why is 4 inches important for zeroing.

The importance of 4 inches for zeroing
Preparation is a major key to properly zeroing any optic.

It’s All About Repeat Performance

As we see more and more shooters exploring red dot sights eventually they will have to install and zero them. We can talk about installing another time, right now we are going to focus on the finer details of zeroing. I wrote a pretty lengthly blog on the subject already, check it out to get caught up; Zeroing a Pistol Mounted Optic. One part I didn’t cover in too much depth was the reason we use 4 inches. It boils down to repeatability. To properly zero a red dot sight the group size must be precise. Firing a 4 inch group from a supported position will give you the ideal shot group to make corrections. The corrections made are based on the group’s location relevant to the point of aim.

Proper Procedures for Best Results

The general zeroing procedure is to take the center of the shot group and measure to the center of the point of aim. Then calculate the adjustments necessary to move the point of impact to the desired point of aim. Fire another group of 4 inches or better to confirm the adjustment. Repeat this process until satisfied with the zero. Using a 4 inch group increases the chances the shot group will be over the desired point of aim. The smaller the group size the greater the zero’s precision. With larger groups there is a chance the actual center of the shot group is not the true point of aim. The resulting bad shots are shooting errors and they are harder to distinguish since the group size is so large.

Shooting Skill Dictates Zero Distance

It is precision that matters when zeroing. Without a high degree of precision, the accuracy may or may not be on target. Shooting repeatable groups is how to achieve the best zero. It is one thing wanting to zero at a specific distance, it’s another thing having the skill to zero at said distance. I believe to truly take advantage of the RDS you want to zero at the furthest distance in common use and that would be the 25 yard line. However, if you can’t repeatedly produce 4 inch groups from the 25 yard line then it is not a “good” zero distance. You could improve your marksmanship skills to tighten your shot group, but that will take work. So, what do you do in the meantime while improving your marksmanship skills? Move the target closer.

Close the Distance

Move the target to a distance where repeatable 4 inch groups are possible. That might be the 20 yard line, or maybe the 10 yard line. If 4 inches or better repeatable groups are not possible at the 10 yard line, the better choice is to invest in marksmanship training. Before investing in a red dot sight build the marksmanship skills up through formalize training. Working with a firearms coach or attending a weekend training course are great ways to develop marksmanship skills. Returning to the red dot sight with good marksmanship skills will ensure the most precise zero possible.

It’s all about knowing yourself and then exploiting your gear to your advantage. Use 4 inches as your guide to choosing your zero distance, then work to improve your marksmanship skills.

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