Prism Scope Versatility: The Battlefield and Beyond

Few optics types achieved legendary status as much the prism scope in the last 20 years of war. Venerable models such as the Trijicon ACOG still appear in video games and movies, as it continues to serve even when considered “last-gen” in some cases. The original concept of a prism scope was to fit the performance of some riflescopes into a smaller, more ruggedized body. Later, 1x models appeared as an alternative to a red dot sight. Although not a do-all optic for all situations, the enduring presence of prism scopes on personal and professional firearms of all levels testifies to their viability.

A product of the '80s, the prism scope would fully blossom during the Global War on Terror. Initially designed as a way to fit the magnification of a traditional riflescope into a lighter, compact package, the designer of the original ACOG, Glyn Bindon, took inspiration from a pair of binoculars. Where the length of a traditional telescoping riflescope required the length of the tube to function, a prism scope could shorten the overall length by reflecting the image inside the body of the sight. With lenses at each end, and a prism in the middle to achieve the required distance between them via reflection, the optic style earned its name.

Prism Scope Merits

Regardless of magnification, two merits allow Prism Scopes to stand out on their own. Because the reticle is etched into the glass, it can operate without batteries, at least in daylight. Second, for people with astigmatism can experience a distorted dot when looking through a reflex sight, but will not suffer this issue with a prism scope.

By etching the reticle into the glass of the optic, it can achieve a greater level of complexity and precision than on a classic reflex sight that relies on a reflected LED. Many magnified prism scope options set themselves apart by including bullet drop compensators as part of their reticles, none as famous as the Trijicon ACOG chevron. While the fame of the ACOG may last, since then many contenders have risen to challenge their hegemony.

The diverse landscape of Afghanistan and the integration of night vision would lead to the development of new methods of setting up a carbine or rifle. Where a red dot sight would be optimal for the confined spaces of urban environments, often mountains, poppy fields, or barren land separated small clusters of structures. The ability to effectively assess and engage enemies at a distance once meant sacrificing close-range performance, until solutions such as the 3x magnifier or offset red dot sights started trickling through the ranks.

With a prism/red dot combo, one could have the advantages of a fixed magnification sight when approaching a target building from distance, and have the ability to quickly transition to a non-magnified MRDS when entering. As a result, many magnified prism scope options integrate a designated mounting point for an MRDS.

Offset vs Piggyback

Prism Scope/MRDS combinations are just one solution to adding versatility to any build. Competing against LPVOs and Red Dot/Magnifier combos, one of the allures piggybacking or offsetting an MRDS brings is the speed of transitioning between magnified and unmagnified options. Simply rolling the rifle or adjusting head position allows the shooter to keep both hands on the rifle, and is much faster than flipping a magnifier on or off, or turning the dial on an LPVO.

Whether mounted on top of a prism scope, or at an offset, adding an MRDS will expand the dimensions of the build. Placing an MRDS on top of a compatible magnified prism scope appeals to some of the same advantages that come with taller mounts for red dot and holographic sights: a more head's up posture when moving through urban environments, and easier passive aiming when wearing Night Vision Goggles. Transitioning between the two will take practice in the daytime, especially when considering the eye releif of the prism scope.

The advantage of the offset option is that the same cheek weld works for both optics. Rolling the gun back and forth aligns the eye with either the prism scope or the MRDS. Some attention must be paid to the model of MRDS and mounting option to ensure proper alignment, but with the popularity of the combination, options are available for lower profile direct mounts, or picatinny for compatibility with more mini reflex sights.

As the MRDS will be used mostly for close engagements, the user has more freedom with what zero they will choose, keeping height-over-bore in mind. Attention to detail improves both options, as the taller piggyback choice balances between versatility with night vision, and the greater distance between their point of aim, and the trajectory of the bullet.

Magnification

Generally speaking, prism scopes range in magnification from 1x to 5x, with the lower power options effectively encroaching on reflex optic territory. As sights like the Vortex Spitfire AR and Atibal SAP sport reticles ideal for fast-paced, close-range shooting, they bring a distinct clarity, as they do not need any coating to reflect an LED. Most prism optics can be adjusted to the user's eye.

For magnified options, 3x and 5x are most popular, with the U.S. Marine Corps going their own way with a 4x ACOG. Designated Environment, Reticle, and Shooter's preference come into play when choosing between various magnified prism scopes. In like America's Upper Midwest, where most shots will be within 300 yards, a 3x prism with a more preferred reticle can outbid a 5x without it. Reticles with Bullet Drop Compensators are built around specific caliber, load, and barrel length combinations, and will require dedicated range time to confirm zero and holds.

Prism Scope Conclusion

The sheer number of Prism Scopes on the market says two things: the concept is solid, and it's up to the buyer to look into where they spend their money. In a world where “just as good as” is often used as a sales pitch, some suspicion is warranted but is not quite an immoveable rule. The following list of prism scopes represents a slice of what options are available.

Atibal SAP

Magnification: 1x
Field of View at 100 Yards: 68 feet
Dot and Ring Size: 3 MOA Dot, 60 MOA Outer Ring
Brightness Levels: 7 Daylight, 1 Night Vision
Length: 2.2 inches
Weight: 4.8 ounces with Low Profile Mount, 5.9 with Co-witness Mount
Approximate Battery Life: Up to 30,000 Hours
Battery: CR 2032
MSRP: $280
URL: atibal-optics.com

The Atibal SAP is a fresh take on 1x Prism Optics. Smallest in its class at time of writing, it resembles popular red dots in form factor, but includes the benefits of a prism. The objective lens brings in plenty of light, and can easily be at home on an AR-15 or Pistol Caliber Carbine.

Vortex Spitfire AR

Magnification: 1x
Field of View at 100 Yards: 79 Feet
Dot and Ring Size: 3 MOA Dot, 44 MOA Inner Ring, 140 MOA Outer Ring
Brightness Levels: 10 Daylight
Length: 4.3 inches
Weight: 11.2 ounces
Approximate Battery Life: Up to 250 Hours at Brightest Setting, Up to 3,000 Hours at Lowest Setting
Battery: AAA
MSRP: $350
URL: vortexoptics.com

The Vortex Spitfire AR functions so similar to a reflex sight, that we included it in the Vortex Red Dot Sight lineup as an honorary mention. Purely a day-time optic, it has seen plenty of success on competition stages. The advantages of 1x prism scope are in full display with the large window and rugged housing.

Sig Sauer Bravo3

Magnification: 3x
Field of View at 100 Yards: 50 feet
Reticle: 300 Blackout with BDC to 600 yards or 5.56/7.62 with BDC to 800 yards
Brightness Levels: 8 Daylight, 3 NV
Length: 6.4 inches
Weight: 22 ounces
Objective Lens Diameter: 24mm
Battery: CR 2032
MSRP: $409
URL: sigsauer.com

Sig Sauer's foray into optics has not gone unnoticed, and now that we are years into the development, the diversity of their lineup included a prism scope that addresses some issues that have plagued the catagory in the past. The Sig Bravo3 is designed to maximize the field of view, giving the user more data when looking through the tube. A large optic in the catagory, it includes removable Picatinny rails, opening up the prism scope to user options when looking to add an MRDS.

Primary Arms SLx 5x36mm Gen III

Magnification: 5x
Field of View at 100 Yards: 18.8 feet
Reticle: ACSS with BDC up to 800 yards
Brightness Levels: 5 Red and 5 Green
Length: 4.3 inches
Weight: 18.4 ounces
Battery: CR 2032
MSRP: $330
URL: primaryarms.com

Primary Arms' take on prism scopes features a capable reticle contained in a rugged and resourceful body. Having the option to switch between a red or green illumination caters not only to multiple users but diverse environments as well. The removable 12 o'clock pic rail hosts the user's MRDS of choice without obscuring vision by sinking it lower than the adjustment caps, achieving a lower profile for piggyback mounted red dots.

Vortex Spitfire HD Gen II 5x

Magnification: 5x
Field of View at 100 Yards: 23.3 feet
Reticle: AR BDC 4 with elevation and holdovers to 650 yards
Brightness Levels: 10 Daylight, 2 NVG compatible
Length: 3.6 inches
Weight: 10.3 ounces
Objective Lens Diameter: 25mm
Battery: CR 2032
MSRP: $350
URL: vortexoptics.com

The Vortex Spitfire HD Gen II 5x represents just how much capability can fit into a small prism scope. The integrated mount, similar to what is seen on optics ready handguns elegantly integrates the option to attach a Viper or Venom MRDS on top, for passive aiming with Night Vision or a quick transition to a red dot. The eye box is forgiving, and out of the box it comes with two different mounting height options.

More on Optics, Sights, and Scopes

• Red Dot Sight Buyer's Guide.
• Vortex Sparc Solar Review.
• LPVO vs Magnifier, Pick your Poison.
• EOTech Magnifier: Force Multipliers.
• Many of the Best 9mm Pistols for 2020 come optics-ready.
• Aimpoint Acro vs Holosun 509T: Battle of Sealed MRDS Optics
• Vortex Red Dot Sight Lineup.

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