A rifleman is a well-balanced marksman. What makes us versatile shooters is the ability to develop a system that allows us to estimate a target’s range, the target’s condition, and to execute a well-aimed shot on the fly. Some people use the irons for this very effectively. Some people spring for optics such as the ACOG with bullet drop compensation. Many of us though, have red dot sights. I think we often put red dots in a box… but the reality is that they can be used effectively for simple distance shooting. I put together a chart to look at two common calibers and explore the dot size in relation to bullet drop with a 200 yard zero.
A Quick and Dirty MOA Explanation for Those Unfamiliar:
1 MOA is roughly equal to 1 inch at 100 yards. For anyone who is unfamiliar with using MOA here is a very basic explanation. Let’s use a 7 MOA red dot sight in this example. At 100 yards the dot would cover 7 inches. At 200 yards the dot would cover 14 inches. At 300 the dot would cover 21 inches. The average shoulder width of an adult male is 18.5 inches. So if you were looking at a target 300 yards out with a 7MOA dot… the body of the target would be completely covered by the red dot. In this example 7 MOA really limits the ability to hit a target at 300 yards. It’s simply too big a dot.
Below is a graphic that shows average sizes that we use when we estimate the range. Shoulder to shoulder is 18 inches. Chin to center of mass is 9 inches. Top of head to COM is 18 inches. Etc.
Some information before we begin. This chart represents different dot sizes and two different calibers are listed. The zero for each projectile is a 200 yard zero. The readings below the dot size represent how large the dot will appear at each range, in inches. So a 2 MOA dot at 300 yards will cover 6 inches. Knowing how to use the dot’s MOA we can make rough estimates based on shoulder width or head size relative to the dot size. For example if we are shooting 7.62×39 with a 7 MOA red dot and find that the target is completely covered shoulder width by the red dot… we can estimate the target is past 300 yards. Adjust your hold over accordingly.
Example 2: shooting 5.56 at a B27 silhouette with a 4 MOA red dot… and the targets head is covered up by the dot, and the dot only covers half the shoulder width, then we can estimate the target to be at roughly 200-250 meters. If the dot covers the body shoulder to shoulder we can estimate the target to be at 450 + yards.
Blue = where the dot starts to obscure the head
Red = where the dot is roughly shoulder width
Ammo: 123 gr 7.62×39 at 2355 FPS and 55 grain 5.56×45 at 3240 FPS
|Yards||7.62×39||5.56×45||2 MOA||3.5 MOA||4 MOA||7 MOA||12.9 MOA Triangle
The chart becomes more useful if we can use it to not only roughly estimate range, but to help us adjust for bullet drop. I range a target with a 4MOA dot to roughly 300 yards. The dot barely covers the face. With a 200 yard zero the 5.56 55 grain XM193 projectile will fall -6.4 inches below zero. If we use the dot hold over on the head of the B27 silhouette and have the bullet drop into the upper chest of the target. Keep in mind this is simply quick and dirty range estimation. In practice you will need to determine what works best for your setup… However, taking an educated shot will better aid us than guesstimation.
The 12.9 MOA triangle is something I don’t have personal experience with. The bottom edge would be used for range estimation, but due to the taper of the tip I think it might take some practice to learn it well.
Getting into the ballpark range with the flatter shooting calibers would lead to hits on target. A red dot can be useful for simple ranging and we can then use the size of the dot to aid us with hold-over. Each setup and caliber will benefit from simply learning your drop and developing a system of hold-over specific to your setup. I like to use the head and the top of the head for hold overs with my 2 MOA dot. It is a very sharp dot so it fits inside a b27 all the way out to 500 yards ergo is not as useful for quick and dirty ranging. I will continue to experiment with dot sizes and different setups.