ACOG VS Red Dot Sight Comparison – Which To Use & When?

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ACOG VS red dot sight - If you have both optics, then how to decide which one to use over another?

Both are great optics and they have their places for particular applications.

Let's compare them side by side


A red dot sight emitter projects the aiming dot on the glass and the reflection is what the shooter sees and uses to aim.

ACOG (Advanced Combat Optical Gunsight) is a fixed magnification prism scope with glass etched reticle that has more details than a red dot sight. It's for accurate distance shooting.

When To Use Trijicon ACOG (3.5X & 4X)

ACOG 3.5X SDO on SCAR 17

Use ACOG 3.5 or 4X for frequent mid range engagement & target identification

The reticle is etched on the glass, and it works without a battery.

For shooters with astigmatism, a prism sight gives the shooter the sharpest reticle for precise aiming. The ACOG also enable the shooter to aim with both eyes open while applying the bindon aiming concept (Takes time to get used to)

Trijicon ACOG Reticle styles basics
acss aurora reticle

ACSS

There are 4+ different types of reticle types available for the ACOG (Chevron tip is the most popular, and now the new ACSS reticle with the fast ranging capability)

USMC shooting HK M27 with ACOG 3.5X

Referenced USMC

“The ACOG® mounted on the M16 service rifle has proven to be the biggest improvement in lethality for the Marine infantryman since the introduction of the M1 Garand in World War II.”

Major General J.N. Mattis | Commanding General, 1st Marine Division | Operation Iraqi Freedom

Pros

  • Built like a tank
  • Detailed reticle with holdover reference points
  • Very positive MOA click adjustment
  • Protected turrets
  • Accepts aftermarket mounts including Quick Release (QD)
  • Ability to accept a piggyback 1X micro red dot sight

Cons

  • 4X32 has super short eye relief distance - Not too friendly for helmet wearing shooters (3.5X is much better)
  • Must center the eye behind the scope to be in the eye box
  • No diopter adjustment to focus the image for shooters with bad eye sight

When To Use A Fixed 1X Red Dot Sight As The Primary Optic?

Daniel Defense DDm4V11 uper with Aimpoint Patrol

A lightweight 1X red dot sight is best used for CQB, close range, and medium-range engagement without any eye relief limitation.

Use red dot for most close range applications including home defense

Wherever the shooter placed the dot is where the bullet is going (assume properly zeroed)

Scalarworks Aimpoint Micro Red Dot Sight Mount POV

It's very versatile for various applications such as combat, hunting, home defense for fast target acquisition.

Red Dot Sight MOA Sizes
M1 iron sight vs micro red dot

Shooters prefer a red dot over iron sights because the aim is much finer and it doesn't obscure the target.

2 MOA red dot sights are the most common, and it's a balanced dot size for precision aim and big enough for the eye to pick up.

Pros

  • Super fast for CQB target acquisition
  • Aim with both eyes open
  • Parallax free reticle allows flexible eye box behind the optic
  • Capable for long range with the use of a magnifier scope
  • Extreme long battery life
  • Protected turrets
  • Accepts tons of aftermarket mounts

Cons

  • Reticle clarity is a challenge for shooters with astigmatism
  • Can't really aim with two eyes open if having bad vision

Side By Side Comparison

ACOG VS Red Dot is pretty much a discussion between prism optics vs red dot. There are also 1X prism optics available.

Field Of View

Red Dot

CQB

romeo5 pov red dot reticle on steel target

Medium Range

aimpoint with vortex micro 3x

With 3X Magnifier Assist - Much better target identification

Insert Image

ACOG

CQB

Not so good for close up acquisition. This is the time to switch to an red dot on an angled offset mount.

Or piggyback mount a Trijicon RMR on top of the ACOG.

ACOG 3.5X on FN SCAR 17

Durability

ACOG is made of 7075 T6 forged aluminum. It's built like a tank as a standard issue for young Marines for hard field use. 

Top tier red dot sights like the Aimpoint Micro T2 can survive lot of physical abuse and continue to work and hold zero. However, cheaper red dots with poor mounts may not be that tough.

Reticle Clarity

sig romeo 5 red dot pov

Red dot sight dot sizes matter a lot for reticle clarity and aiming accuracy. The dot appears differently for everyone with varying eye sights.

Moisture, lens smear, oil can make the dot less crisp until it's cleaned

People with astigmatism will typically see this through a red dot sight:

shooters with astigmatism see this

When the eyesight is corrected the blurriness goes away for the most part. However, any smear on the glass or moisture on the emitter will refract the dot projection poorly.

ACOG POV 4X

For ACOG on the other hand has the best reticle clarity and light transmission through the glass.

The glass-etched 5.56 NATO calibrated BDC reticle (TA31) inside the ACOG is crisp for the eye to acquire. (7.62mm NATO BDC reticle offered as well)

The fine Chevron tip has an infinite fine aiming point for a precise shot than a red dot that generally covers up the target downrange.

scar17 with Trijicon ACOG with RMR piggyback setup

Shooters need to be cognizant of how much light the fiber optic is collecting, which can lead to a reticle being too bright. Often people put a piece of tape over the fiber optic to prevent over brightening the reticle so the shooter can aim easier.

A over brighten reticle inside ACOG can block the target especially when they are small down range.

Size & Weight

SCAR 17 with ACOG 3.5X

Takes up most of the top rail space 

Adds ~ 13.1 Oz To Your Setup

Takes up - 5.8" rail space for 4X32

8" rail space for 3.5X35

scalarworks aimpoint micro on mk18

Red dot sight is always a lighter & more compact setup than an ACOG scope. 

Adds ~ 5 - 6.2 Oz To Your Setup

Takes up 2.7" - 7" rail space (Based on optic size)

Mounts

Most red dot sights come with factory mounts. Aimpoint and Trijicon are the only two companies that sell some of their products without mounts, so the buyer has remember to buy mounts.

There are more optic mounts made available for red dot sights on the market than the ACOG. 

Different optic heights are available for red dots but not for ACOG.

scalarworks leap mount tightening
Geissele super precision ACOG scope mount

Some companies do make ACOG aftermarket optic mounts, and they are much better at holding zero and stay tight on the rifle than the default thumb screw mount. 

The top ones are:

  • LaRue Tactical QD lever mount
  • Geissele Super Precision Mount
  • American Defense 

Key Takeaways

  • Red dot is fast for CQB, and a magnifier scope can extend its range
  • Red dot MOA sizes matter for dot clarity and precision aim
  • Parallax free red dot gives the shooter the ability to aim without centering the eye behind the optic
  • ACOG's reticle never dies and it's super crisp for shooters with astigmatism
  • A fixed magnification ACOG is great for a dedicated mid range rifle

Ying Xu

US Air Force veteran nuclear weapon officer. Aerospace engineering bachelor's degree from the University of Kansas. Experienced as a certified NRA range safety officer. Working as a search engine expert for BadAssOptic.com