Monstrum Tactical 3-9×32 AO with Illuminated Range Finder

9 Total Score
Monstrum delivers monster value with this magnified rifle scope.

If you're looking for an inexpensive tactical scope that will give you long-range capabilities, and you don't want to spend more than what your rifle is worth, this 3-9X scope should be on your list of considerations.

  • Adjustable objective lens
  • Illuminated BDC reticle
  • Nitrogen filled tube eliminates condensation build up
  • Extremely inexpensive for its feature set and performance
  • Includes O-rings
  • No mounting points for reflex sight
  • No lens caps
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Monstrum Tactical 3-9×32 AO Rifle Scope with Illuminated Range Finder Reticle and High Profile Scope Rings Review

Monstrum Tactical designs, manufactures, and distributes tactical scopes and other gear from their headquarters in Aliso Viejo, California. Some of their other product lines include lights, lasers, rails, and various other firearm accessories. The Monstrum Tactical S3932-R-RAO clicks in around a pound. It’s got a 1 inch diameter tube and will need a high mount, which means we’re looking at a one-third co-witness if you have backup iron sights.

Inside the box you’ll find a pair of scope rings, which allow you mount to just about any flat top rail. Included as well are a set of lens caps and one battery for reticle illumination.


Detailed Specifications


Product Picture
Reticle Type
Tube Size
1 inch
Adjustment Markings
1/4 MOA
Objective Lens Size
Adjustable Objective
Parallax Calibration
37.7-14 Feet
Eye Relief
4.2-3.2 inches
Eye Relief
4.2-3.2 inches
13.9 ounces
Battery Type
Additional Features
  • 5 levels of brightness
  • Sealed, nitrogen charged tube
  • Water and fog resistant
  • Includes scope rings

Monstrum Tactical 3-9X32 Overview

The Monstrum Tactical scope features an illuminated reticle in order to aid in target acquisition during low light scenarios. It’s powered by a CR2032 3V batter, which is located in the illumination turret. You’ll need a coin to unscrew the cap, and the battery installs with the negative side down.

The S3932-R-RGAO (its full model number) has a range finder reticle to aid you in estimating range to target. The has marks are at 100 yard increments, with “bumps” for 50 yard increments between 300 and 400 yards, as well as 400 to 500 yards. At 25 yards, the X-axis provides an approximate shoulder width gap between the thickness of the horizontal line.

The Monstrum Tactical Scope features an AO (adjustable objective) lens, with a ring to help make changes to the objective lens as to eliminate parallax. Parallax is when the lenses in the scope do not provide the appropriate picture of the target in a way that makes shifting your head from one side to the other cause the crosshair to move. This reduces accuracy. An adjustable objective lens will aid in eliminating parallax, as opposed to a fixed lens, which is dialed in for a specific distance (ie 100 yards.)

Eye relief for the Monstru Tactical S9323-R-RGAO is about three inches. The turret caps can be unscrewed with a coin to reveal 1/4 MOA windage and elevation adjustments. Once you’ve got it dialed in, you can be assured that its aircraft-grade aluminum, nitrogen sealed body, and various red and green lighting levels will deliver accurate performance as a tactical scope.

What we liked

This scope checked off all we like in a scope of its class. It has an adjustable objective lens, which is great for scopes of varying magnification levels, and practical application in field scenarios not tied to stationary targets as it aids in range estimation. The nitrogen filled tube prevents condensation. It has varying levels of illumination, both in red and green variants. The reticle has has marks which aid in bullet drop compensation. We also liked that it came with its own rings.

What we didn’t like

While we don’t ever consider this a true negative, we always point out whether one of these scopes will co-witness or not. Being that it starts at 3X magnification, we’re not sure you’d ever want it to. If you think you’ll ever need to quickly switch between different sights in a rapidly changing scenario, you’d be wise to consider 45-degree angle sights. This scope does NOT have any mounting points for a reflex sight. It also does not come with any lens caps.

Customer Reviews

This is great scope for the money. Very easy to use and intuitive. It took me about 20 rounds to zero my AR-15 at a 25 yard range...that was probably more about my shooting and limited support as I was leaning over a barrier without a shooting bag, or sled...but once dialed held well. The AO adjustment is great! It provides a very clear sight picture as well as helping to fairly accurately estimate the distance to the target. Love the red or green reticle options...Update Aug 2015: I have been using this scope for 4 months...still VERY impressed.
MelissaT - April 19, 2015
Wow, you just can't beat the sexiness and features of a 300 yard capable scope for the price. Granted the optics are not the same clarity as a Zeiss (did you expect it to be for 6x - 20x less money?) but is more than adequate for everyone who is not a professional sniper or Navy SEAL operator. I also love the lighted range finding reticle. It is NOT mil-dot but uses an intuitive system to allow you to estimate bullet drop out to 500 yards. Add in an adjustable AO, an average 3" eye relief, no perceptible parallax, solid construction and feel, and included mounts you get a LOT of scope. Also the scope DOES include flip up dust covers not pictured. At the end of the day you have to ask yourself what you want in a scope. Sure, bragging rights at the range will definitely go to the guy with a $2,000 Zeiss Victory Scope sitting on top of his tricked out AR-10 dripping in MAGPUL furniture and Punisher decals. BUT you will have saved thousands of dollars and have a beautiful scope that will absolutely dress up your AR. With the money you save you can use for shooting lessons, and taking out hot chicks - which will make you a better shot and a more popular guy than the douche in the next lane.
WarEagleX - December 28, 2014
I decided to go with this scope because of the overall length being 9 1/2 inches and it's adjusting capabilities. I used this on my AR-15 chambered in 7.62x39 and it has held up great. Lighted reticle is good, but on highest setting is a little overwhelming in brightness (simple just turn it to a lower setting). I was able to shoot once, set the windage and elevation as needed and my second shot was dead center bullseye (2 shot sighting method). For the price this lil scope is a great buy and would recommend it to anyone and already have. Thanks.
Frank Murray - December 30, 2014


The Monstrum Tactical S3932-R-RGAO is a fantastic option under $100. If you’re not expecting to take it into battle, or rely on it for hunting food that you need to live off of, it’s a great option for the hobby shooter. Many times these more inexpensive scopes can be cheaply made as well, but for many people who need a tactical scope, these options can be a perfectly fine option. We liked the price, the features, and performance. This Monstrum Tactical Scope should be on your list of considered optics if you’ve just finished an inexpensive AR-15 build.


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Monstrum Tactical 3-9x32 AO Rifle Scope with Illuminated Range Finder Reticle and High Profile Scope Rings

Enter your model number to make sure this fits.; Adjustable 3-9 times magnification, for targeting out to 300 yards and beyond; Adjustable reticle illumination with 5 brightness levels in both red and green, allowing for better reticle visibility at night or in low light environments; An...

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Monstrum Tactical 3-9x32 AO Rifle Scope with Illuminated Range Finder Reticle and High Profile Scope Rings

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  • Adjustable 3-9 times magnification, for targeting out to 300 yards and beyond
  • Adjustable reticle illumination with 5 brightness levels in both red and green, allowing for better reticle visibility at night or in low light environments
  • An adjustable objective lens Ð or AO - that allows for sharper focus of the target image, elimination of parallax, and range estimation
  • A range finder reticle with markings that allows you to estimate range or compensate for bullet drop
  • Aircraft grade 6061 aluminum scope body with a sealed, nitrogen-charged tube for resistance to water and fog