MOA and Red Dot Sights

The choice of the correct MOA (minute of angle) for your red dot sight is critical. A red dot or reflex gunsight is a major investment. A Trijicon or Aimpoint will set you back the price of a new Glock 19 Gen5 MOS. The Truglo RMR (rugged mini red-dot) weighs in at about half that price but it’s still a sizeable investment. So let’s look at the apparent size of the dot on the target and what will be optimum for you.

What is MOA?

A degree is divided into 60 even parts called ” minutes of angle.” This minute of angle subtends an arc of different lengths depending on the distance from the origin or center of a circle.

High School Protractor MOA
MOA (minutes of angle) explained

So at 100m, the arc length of 1 MOA (minute of an angle) is 29mm and because it’s linear, at 1000m, 290mm. Realistically, I am going to stop right there. Most of the technical stuff written about MOA – and there’s tons of it – is for long distance precision shooting. How is this applicable to Red Dot Reflex sights for handguns? The MOA of the sight will determine how big the dot appears on the target.

Optimum Dot Size

Initially please understand that I use the term “Red Dot” in a broad way. The fact is that reflex or red dot sights are available with a variety of different reticles. As a result Red Dot sights are available with dots, circles, crosshairs, cruciforms, triangles and many other geometric shapes or combinations of them. For simplicity we are going to discuss dot reticles only. Generally the smaller the dot the easier it is for fine aiming. Small dots however are not great for rapid target acquisition. A fat bright dot (or other reticle) allows you to quickly come onto target but are not great for a fine aim.

Reflex Sight Blooming

Blooming Effect Red Dot Gun Sight
Red Dot reflex sights Blooming effect related to intensity

Reticles that have adjustable brightness have a tendency to look larger at high brightness. This can however be used to advantage. When the brightness is dialled back the dot appears smaller and is then more suitable for finer aim. The Japanese made Shilba 17 x 24 demonstrates this effect particularly well.

MOA, red dot, red dot sizes,
Red Dot Sizes on a man-sized target

Relation between MOA and Red Dot Sights apparent dot size

The correlation between MOA and a Red Dot Sights apparent dot size provides these figures. At 25m a 3MOA is 21mm and at 25m a 7 MOA is 49mm. Drop back to 15 m and a 3MOA red dot is an apparent 15mm. A 7 MOA red dot, however, at 15m is 31 mm.

So what does this mean for a pistol shooter? A 7 MOA RMR will obscure the bull and the 8 and 9 circle on a 25m NRA pistol target. So not ideal for a fine aim target work. The same fat dot though is perfectly fine for shooting an IPSC popper at 30m though.

The best rule of thumb to follow here to to choose the smallest MOA site that gives you good and rapid target acquisition. If your field is more CQC/self defence related err towards a larger reticle. If accuracy and fine aim are your priorities go for a smaller dot size. I certainly wouldn’t go finer than 3MOA on a handgun though.

Red Dot on a Roni

 As a result of the ability of a Glock Roni combination to shoot passable groups out to 70m and beyond the temptation is there to scope the micro Roni with a small MOA dot of around 1 or two MOA. Much like you would do an AR. Again the caveat here is to ensure that for a CQC scenario your fine reticle is large enough for rapid target acquisition.

3MOA red dot vs 7MOA red dot
IPSC 300mm popper at 30 m and a 3MOA red dot vs 7MOA red dot

2 thoughts on “MOA and Red Dot Sights

  1. Please advise when the Glock 19 Gen 5 and the MOS version will be arriving in stock.

    Many Thanks,


    1. Hi Nish – hopefully November . Many thanks

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