Best M4 Optics and Scopes – Buying Guide and Reviews 
The M4 is extensively used by the US Armed Forces and has mostly replaced the M16A2 assault rifle. However, it has different characteristics, including a shorter barrel, that require other considerations when choosing the best optics and scopes for the M4.
- 1 What Are the Basics of an M4 Optic and Scope?
- 2 What Magnification Do You Need for the Typical Use of an M4 Scope?
- 3 What Are the Best M4 Optics and Scopes?
- 4 Best Red Dot, Holographic, and Prism Sights for the M4
- 5 Best Scopes for the M4
- 6 Final Thoughts
What Are the Basics of an M4 Optic and Scope?
The M4 is essentially a shorter version of the M16. It was designed as an alternative to the AR-15 and M16 rifles for dealing with close combat.
The Colt M4 carbine was adopted by the military in 1994 and remains a popular choice due to its speed and accuracy at shorter ranges. It also features a collapsible stock and the ability to switch between three-round bursts and fully automatic firing. These features also affect the selection of optics and scopes for the M4.
The M4 is typically used for short- to medium-range tactical situations. Civilians cannot legally own an M4 in the United States but may purchase a modified AR15 with a shorter barrel. Modified carbines are available that closely match the characteristics of the M4 without the fully automatic firing option.
The M4 alternatives are often used for hunting small, fast animals at short to medium ranges of 100 yards or less. Typical targets include turkey, raccoon, rabbit, badger, fox, and coyote.
As you start to reach beyond 100 yards, the quality of the glass becomes more crucial for providing optimal clarity. Look for scopes from reputable manufacturers known for using crystal clear glass. Fully multicoated lenses also ensure better performance due to superior light transmission.
You will also want a wider field of view (FOV) for ranges of 100 yards or more. However, scopes with greater magnification tend to provide a smaller FOV. For example, a 3X scope may offer a FOV of about 30 feet at 100 yards, while a typical 9X scope may only offer a FOV of 14 feet. With a smaller FOV, it becomes harder to track fast-moving animals.
Longer distances also require windage and elevation adjustments. Many hunters prefer to use scopes with ballistic turrets instead of target turrets when they need to acquire a target quickly. The ballistic turrets allow you to make larger adjustments and are often capped to keep the settings locked in.
Another consideration is the parallax setting, as a fixed parallax of 100 yards can impact your accuracy at shorter distances. If you plan on shooting small game at close ranges, look for scopes with adjustable parallax. Adjustable parallax turrets often allow you to set the parallax from 10 yards to infinity.
What Magnification Do You Need for the Typical Use of an M4 Scope?
For hunting at short distances of 50 yards or less, the typical hunter does not need magnification. Look for quality optics, such as a red dot sight, holographic sight, or prism sight. These optics complement the characteristics of the M4 carbine, including faster target acquisition and greater accuracy at closer distances.
Red dot sights (reflex sights) use an LED emitter to direct a beam at the glass, which then reflects the beam to your eyes to create the appearance of a red dot on the reticle. As a reflex sight offers unlimited eye relief, it allows for faster target acquisition. However, they are not available with magnification.
Holographic sights also create the appearance of a red dot but use lasers and mirrors instead of an LED emitter. Unlike red dot sights, you can find holographic sights with magnification. They also tend to offer a larger field of view.
Prism sights use a prism to reflect light through the optics. They are typically a little bigger compared to red dot sights but are also available with fixed magnification.
At distances beyond 50 yards, you may need at least 2X or 3X magnification. A 3X scope can make a target at 100 yards appear about 33 yards away. For distances beyond 100 yards, you may require 4X or greater magnification.
As the FOV tends to get smaller with greater magnification, you should avoid using more magnification than you truly need. Keep in mind that the M4 has an effective firing range of about 550 yards. M4 alternatives, such as the AR-15 with .223 rounds, offer about the same effective range.
Using a variable magnification scope provides increased flexibility for the M4 and AR-15. For example, scopes with 3-9X or 4-12X power can cover the entire effective range of the rifle. However, a 1-6X scope may be better suited for switching between short- and long-distance targeting.
What Are the Best M4 Optics and Scopes?
To save you from the hassle of comparing options, here is a roundup of the best M4 optics and scopes.
Best Red Dot, Holographic, and Prism Sights for the M4
Vortex Spitfire 3x Prism Scope
The Vortex Spitfire 3X Prism Scope is a relatively affordable option for those who want to set their sights on targets 100 yards or further quickly. It features fixed 3X power to bring distant targets closer without needing to deal with variable magnification.
The Spitfire uses a custom bullet-drop compensation (BDC) reticle intended for use with 5.56 cartridges and ranges up to 500 yards. The glass-etched reticle also includes illumination using a prism assembly.
As with red dots, a prism sight can add an illuminated dot to the reticle. However, when the battery dies, you still have a visible reticle for use without illumination. The Spitfire allows you to switch between red, green, and no illumination.
Using the prism assembly also allows for a more compact design. The Spitfire is just 5.5 inches long and weighs 15.4 ounces. It also has a field of view (FOV) of 31.5 feet at 100 yards.
As with most scopes from Vortex, the Spitfire features durable construction and fully multicoated surfaces for increased reliability and light transmission.
The Vortex Spitfire includes a couple of drawbacks, including the 2.8-inch eye relief. Compared to other scopes for the M4, you need to put your eye a little closer to the glass. The prism design also offers shorter battery life compared to a typical red dot sight.
- Fixed 3X power for “always ready” magnification
- Multiple brightness settings and illumination options
- Includes fully multicoated lenses
- Features a compact design
- Offers limited eye relief
- The battery may not last long at the highest setting
The Aimpoint PRO is a red dot sight with multiple brightness settings and a reasonable price. Unlike the prism sights, the Aimpoint PRO projects a red dot on the reticle using an LED emitter, which offers far superior battery life. You can enjoy up to 30,000 hours of continuous operation on a single battery.
The red dot sight has 1X magnification and unlimited eye relief. It does not bring your target closer. It complements your iron sights by placing a red dot in the center of the optic, making it a good choice for ranges that do not require magnification, such as 50 yards or less for the typical marksman.
Compared to using a power scope, the Aimpoint PRO red dot optics allows for quicker target acquisition. You can line up your shot through the optic no matter how far away it is to your eyes.
The design is a little bulky compared to the prism sight, measuring 6.75 inches long. However, it is also a reliable sight with a durable design for use in any environment. It is shockproof and submersible up to 150 feet. The lenses also feature flip-up covers while the turrets are capped.
- The battery can last up to three years.
- Allows for faster target acquisition at close ranges
- Durable design for use in harsh environments
- The design is bulky compared to prism sights
Sig Sauer Romeo5 Red Dot Sight
The Sig Sauer Romeo5 is an affordable red dot sight with a compact design. Due to the sight’s low price, it does not offer the most incredible clarity or illumination. However, it should still help improve your accuracy for short- or medium-range targets.
While the sight has 10 illumination settings, including two night-vision settings, it does suffer in low-light conditions. The advantages include enhanced battery life and easy operation.
Buttons on top of the sight control the illumination settings. The Romeo5 also features motion-activated illumination (MOTAC). It automatically turns on when it senses motion and powers down to conserve energy, extending the battery life up to 50,000 hours.
This red dot sight also has coin-style turrets instead of ballistic or target turrets. The coin-style turrets require a tool to adjust but are less likely to be accidentally adjusted, making it easier to retain your settings.
The design is relatively compact, measuring just over five inches long and weighing just over eight ounces. It is also fogproof, shockproof, and waterproof up to one meter.
- One of the most affordable M4 sights
- The red dot settings are easy to adjust
- Compact, lightweight design
- It does not work as well in low-light settings
Vortex Optics AMG UH-1 Gen II Holographic Sight
The Vortex Optics AMG UH-1 Gen II is a holographic sight that produces a red dot on the reticle. However, unlike prism and reflex sights, it uses lasers and mirrors to create the dot. This allows for smaller dot sizes, such as the 1 MOA dot on the AMG UH-1.
The AMG UH-1 is also a 1X sight. It is intended for use in close quarters by military and law enforcement professionals. However, hunters may also benefit from the fast holographic display and the large field of view. The holographic dot also stays on target. No matter where you point your rifle, the dot remains aligned with the muzzle.
While some people may dislike the lack of an etched reticle, the holographic sight provides a large viewing window for unlimited eye relief.
The Vortex Optics AMG UH-1 Gen II mounts on rifles using Weaver or Picatinny rails and features a quick-release mount. It has a relatively low profile and smaller size compared to other holographic sights. It measures 3.9 x 2.7 x 2.1 inches.
- One of the smallest sights for the M4
- Provides a large viewing window for a bigger field of view
- Works well in all light conditions
- The battery does not last as long compared to red dot sights
EOTech 518 Holographic Sight
The EOTech 518 is a holographic sight with a rectangular window and a clear red dot. With 20 brightness settings, you can easily see the red dot in any lighting conditions. It is also one of the most reliable sights, as it continues to display the red dot even when the window is obscured or shattered.
The EOTech 518 is another good choice for those who need to quickly lock their sights on a target, as the holographic display offers unlimited eye relief and allows you to aim with both eyes open.
The EOTech is compatible with magnifiers, which also increases the size of the dot. Without magnification, the dot is 1 MOA in size.
Compared to the Vortex Optics AMG UH-1, the size of the EOTech 518 sight immediately stands out. It measures 5.6 x 2.2 x 2.9 inches. Instead of coin batteries, the 518 holographic sight uses two AA batteries, which require a bulkier design. However, the AA batteries also offer longer battery life, with up to 2,500 hours of continuous use.
- Provides a clear red dot in all lighting conditions
- Compatible with magnifiers
- Offers up to 2,500 hours of operation
- The design is a little bulky compared to other sights
Best Scopes for the M4
Trijicon ACOG 4×32
The Trijicon ACOG 4×32 is the scope that is most often associated with the M4. In fact, the Advanced Combat Optical Gunsight (ACOG) was designed specifically for the M4 and M16 rifles.
The ACOG is the most used scope in combat due to its durability and reliability. The scope is made with aircraft-grade aluminum alloy to create a nearly indestructible product.
It also features battery-free illumination. The tritium/fiber optic creates an illuminated reticle and automatically adjusts the brightness to accommodate the available light.
Each model offers fixed-power magnification. The 4×32 model is a common choice for those who need to switch between short ranges and long ranges quickly.
For example, with 4X fixed magnification, objects at 100 yards appear about 25 yards away, which is close enough for most hunters to hit their mark. You can use the ACOG as close-quarter combat (CQB) sight with both eyes open at closer ranges.
The Trijicon ACOG has a FOV of 36.6 feet at 100 yards. At greater distances, you can adjust the windage and elevation using the capped ballistic turrets. It also features a bull-drop compensation reticle for compensating at distances up to 875 yards, which exceeds the effective range of the M4.
- Wide field of view at 100 yards
- Suitable for shooting with both eyes open at close ranges
- Provides battery-free illumination for hunting at dusk or dawn
- One of the more expensive options
Vortex Optics Strike Eagle 1-6×24
The Vortex Optics Strike Eagle offers increased versatility thanks to its 1-6X power magnification. At the low end, the scope provides true 1X magnification. You can bring objects that are 300 yards away to just 50 yards through the reticle at the high end.
The magnification ring is visible without pulling your eye away from the scope, making it easier to adjust on the fly. It also has a fast focus dial for quickly focusing the eyepiece.
The Strike Eagle includes an illuminated BDC3 reticle for bullet drop compensation at longer ranges. The clarity of the glass is not the greatest, but you are unlikely to notice the limitations of the glass outside of the nighttime.
The surfaces include antireflective coatings while the lenses are multicoated to reduce glares and increase light transmission.
The scope is durable and includes the standard O-ring seal to make it waterproof and fogproof. It is also made with aircraft-grade aluminum to protect against shock damage from the recoil of the carbine.
- Suitable for close-range or long-range use
- Features a durable design
- The magnification and focus are easy to adjust
- Relatively affordable scope
- The clarity of the reticle decreases in dark conditions
Leupold VX-Freedom 3-9X40mm Riflescope
The Leupold VX-Freedom is a midrange scope with 3-9X power magnification and a 40 mm lens. It provides a decent field of view at close to medium range, but the FOV becomes limited at full magnification.
The scope uses ¼ MOA finger click turrets for windage and elevation adjustments. They are not capped, which may increase the risk of accidentally adjusting them.
Despite a few limitations, the VX-Freedom stands out for the clarity of its reticle compared to other scopes in the same price range. The Leupold scope uses the twilight light management system to add extra minutes of shooting light and reduce glare, resulting in a crisper image in low-light settings.
The scope includes many standard features, including an anti-glare, matte finish, and a fogproof, shockproof design. The 3-9X magnification is suited for almost any situation, except when pushing the limits of the M4’s effective range of 550 yards. With 9X magnification, an object at 550 yards appears about 61 yards away.
The Leupold VX-Freedom is available with several different reticles, including a duplex reticle, a duplex CDS reticle, a hunt-plex reticle, and a tri-MOA CDS reticle. The CDS reticles are a custom dial system for more straightforward bullet drop compensation.
- Available with custom bullet drop compensation reticles
- It offers a versatile option for shooting at different ranges
- Provides greater clarity compared to similarly priced scopes
- The turrets are not capped
- It has a limited field of view at full magnification
Vortex Optics Crossfire II 4-12×44 V-Plex
The Vortex Optics Crossfire II is recommended for long-range targeting, as it includes 4-12X power magnification and a 44 mm lens. You can reach the full effective range of the M4 carbine, which is about 550 yards. The scope also has generous eye relief and a fast-focus eyepiece, allowing you to find and track your target faster.
As you are likely going to need to adjust for windage and elevation at greater distances, the scope uses finger turrets. You can easily adjust the turrets with MOA clicks that can be reset to zero after you sight in. The turrets are also capped to prevent accidental adjustments.
The Crossfire II is durable and suitable for use in any setting. It includes single-piece tube construction using aircraft-grade aluminum. It is also O-ring sealed and nitrogen purged to provide a fogproof, waterproof design.
The lenses are fully multicoated for greater light transmission. Unfortunately, scopes in this price range use lower-quality glass. You are likely to notice blurring in the corners of the reticle in low-light settings.
- Provides optimal magnification for up to several hundred yards
- The durable design should hold up well in rugged conditions
- The turrets are easy to adjust and include caps
- It offers less clarity in low-light settings
Selecting the best M4 scope or optics depends on how you intend to use the carbine. The main factors include the range that you need to cover and the environment.
If you mostly target critters within 50 yards, you may not need magnification. A red dot sight, such as the Sig Sauer Romeo5 Red Dot or the Aimpoint PRO can help you acquire your target without having to hold your M4 within inches of your face. The holographic sights also allow you to aim with both eyes open but tend to offer less battery life compared to the red dot sights.
For medium-range targets at distances of 50 to 100 yards, consider using 2X to 3X magnification. The Vortex Spitfire offers 3X fixed magnification, while the Vortex Strike Eagle offers 1-6X variable magnification.
The M4 and M4 alternatives are not typically used for long-range shooting. However, if you want greater flexibility, you may prefer a scope with more magnification. The Leupold VX-Freedom and the Vortex Optics Crossfire II may help you hit targets several hundred yards away.
The Trijicon ACOG 4X32 is another versatile option and the most popular scope for the M4. It offers battery-free illumination and a wide field of view.
No matter what type of scope or sight you want, ensure that it is compatible with the rail system on your rifle.