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 and the BEST choice for shooters with astigmatism.
When To Use Trijicon ACOG (3.5X & 4X)
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)
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)
“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
- 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
- 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?
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)
It's very versatile for various applications such as combat, hunting, home defense for fast target acquisition.
For more on this topic, please check out our detailed red dot sight beginner guide
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.
- 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
- 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
With 3X Magnifier Assist - Much better target identification
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 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.
Red dot appears differently for everyone with varying vision.
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:
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.
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.
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
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
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)
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.
Check Out: Scalarworks LEAP Aimpoint Mount Review
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
- 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