I became interested in the AR-15 platform in the mid-1990’s. Prior to that, I was a member of my former agency’s SWAT Team and was issued an HK MP-5. M-4-style carbines are now at the forefront as they can be used up close as well as at distance.

The updated MRO SD is slightly larger than the author’s older unit but the enhanced features make the additional size worth the increase.

At one point, I owned more than a few AR platform rifles but I have narrowed it down considerably. My need for a carbine at this time in my life has changed greatly as I am no longer in law enforcement and I am certainly not going to war. I have one “go to” carbine and have set it up to fill my perceived need. I want it to be sleek, light, easy to use and void of unnecessary accessories. It’s reliable, has an optic, sling, and compact weapon light. It has a skeletonized stock and I use 20-round magazines to further enhance its compactness. I have thought about adding either a variable powered optic or a magnifier to increase “reach,” but have been reluctant to do so as adding one of these would add bulk of my sleek, light carbine.

While zeroing distance has been long debated, I have found the 36-yard zero works just fine for me while using my Trijicon MRO dot optic. I have been able to hit a ten-inch gong plate at 300 yards, so my thought was why do I need additional optical enhancement? Life is funny as just about the same time I finally had this decided in my mind, I was walking the floor at the 2025 NRA Convention and stopped into the Trijicon booth and came across the updated version of the MRO, the MRO SD and their palm-sized 3X magnifier.

The Trijicon MRO (Miniature Rifle Optic) is a compact reflex sight intended for use on all long guns to provide fast on target acquisition. Like most reflex sights, the MRO is designed to be used with both eyes open, providing the shooter with enhanced situational awareness. The MRO also features ambidextrous brightness controls, sub-flush adjustment knobs, advanced lens coatings, and a fully sealed, waterproof, hard anodized forged 7075-T6 housing.

The new 3X Magnifier is quite light and compact. It will literally sit in the palm of your hand.

The MRO SD has been redesigned to offer a much longer battery life. The red dot model offers 2.5 years while the green dot offers 3 years. It also offers improved windage and elevation over its predecessor, and it is designed to maintain tight zero retention requirements if dropped or otherwise abused. The brightness adjustment dial is usable with either hand without having to remove the shooter’s hand from the fire control. The capless design uses sub-flush adjustment knobs which eliminates lost caps, snag hazards and ensures against inadvertent re-adjustment or loss of zero. The advanced electronics are warrantied for 5 years while the multi-coated lenses provide superior clarity and light-gathering capabilities with zero distortion for a crisp dot reticle. The re-engineered objective lens allows for enhanced optical performance and magnifier compatibility.

As good as the MRO SD appears, what really caught my eye was the compact magnifier. This palm-sized unit offers a submersion depth of 33 feet, an adjustable quick release flip to the side mount and a field of view of 37.5 feet. The adjustment range of the magnifier is 60 MOA with an objective lens of 21mm. While these features sound great, what most end users want to know is will the updated MRO and magnifier combination enhance their performance? Only a trip to the range will answer that question.

The Trijicon MRO SD and 3 X Magnifier make for a potent, but compact, package on the top of any AR-style carbine. The flip mount for the magnifier is easy to use but locks solidly in place.

I could not use my gun club range for this test as it offers 100 yards as a maximum distance. While this is just fine for my typical practice, I felt like the 3 X magnifier “deserved” a little more distance for a proper test. I reached out to a buddy who owns a farm and he allowed me to set up an impromptu range. I zeroed the MRO SD at 36 yards using a bench rest on a three-inch square sticker of the type I normally use as a pistol target. Like most optics from Trijicon, the MRO SD was mostly zeroed at the factory and it only took a few clicks left and a few clicks up to get it right where I wanted it. I fired only four rounds. After the close zero, I moved back to 300 and assumed a grounded bench rest position to see if I would be close. My target was an AR-500 12-inch gong plate suspended from two chains. Since my carbine is intended for combative purposes, I felt like this “minute of chest cavity” test would be more than valid for my intended purposes.

Spauling keeps his primary carbine as light, sleek and simple as possible. The new Trijicon MRO SD and 3 X Magnifier enhance its capability without adding excessive bulk.

I first tried to hit the plate with the MRO SD alone just to see where I stood. It took a few rounds, but I was able to hit the plate after a few tries. I then flipped up the magnifier. I should note that the flip up mount that came with the magnifier was quite positive, locking the optic in the up or down position solidly while at the same time being easy to operate. With the magnifier flipped down, I was able to flip up my irons and shoot through the MRO with ease. Some will criticize me for not having the irons up all of the time, but these old eyes don’t need any additional “clutter” in the sight picture.

While I was able to hit the plate with the dot optic alone, it was much easier with the magnifier in place. This is not surprising; isn’t that what a magnifier is for? If the target is more visible then accuracy will be enhanced. Like all products from Trijicon, the quality and durability of the MRO SD/ 3X magnifier are readily apparent. The view is crisp and clear with no distortion, even when mating the two optics.

They are not the cheapest options on the market, but they will likely last you the rest of your life and sometimes buying once can save money. When was the last time you “saved money” only to spend more correcting your mistake?

Yeah...me too.

- - Dave Spaulding