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Monstrum

Monstrum Guardian Series AO Rifle Scope with Parallax Adjustment

    • Based on 1,326 reviews
Condition: New
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Availability: In Stock.
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Arrives Saturday, May 10
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Style: Guardian | 3-9x40 AO


Features

  • Adjustable 3-9 times magnification, for targeting out to 600 yards and beyond
  • An adjustable objective lens or AO - that allows for sharper focus of the target image, elimination of parallax, and range estimation
  • Aircraft grade 6061 aluminum scope body with a sealed, nitrogen-charged tube for resistance to water and fog
  • Precision 1/4 MOA/click windage and elevation adjustments with locking turrets
  • Package includes High Profile Picatinny/Weaver Scope Rings and set of flip-up lens covers

Brand: Monstrum


Color: Black | Picatinny/Weaver Scope Rings


Style: Guardian | 3-9x40 AO


Sport: Hunting


Item Weight: 15 Ounces


Material: Aluminum


Magnification Maximum: 9 x


Objective Lens Diameter: 50 Millimeters


Magnification Minimum: 3 x


Compatible Devices: Rifle


Brand: ‎Monstrum


Color: ‎Black | Picatinny/Weaver Scope Rings


Style: ‎Guardian | 3-9x40 AO


Sport: ‎Hunting


Item Weight: ‎15 Ounces


Material: ‎Aluminum


Magnification Maximum: ‎9 x


Objective Lens Diameter: ‎50 Millimeters


Magnification Minimum: ‎3 x


Compatible Devices: ‎Rifle


Mounting Type: ‎Weaver Mount


Night vision: ‎No


Eye Relief: ‎3 Inches


Model Name: ‎SG3940AO


Manufacturer: ‎Monstrum


Reticle Type: ‎Crosshair


UPC: ‎810088810800


Item Package Dimensions L x W x H: ‎15.79 x 3.5 x 2.95 inches


Package Weight: ‎0.83 Kilograms


Brand Name: ‎Monstrum


Part Number: ‎SG3940AO-B


Included Components: ‎Guardian Scope, One Pair High Profile Scope Rings, One Pair Spring-Loaded Flip-up Lens Covers


Date First Available: June 22, 2022


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Saturday, May 10

Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

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Top Amazon Reviews

    • Excellent Scope
Style: Guardian | 3-9x40 AO
Review Image by Melissa Follett Melissa Follett
Review Image by Melissa Follett Melissa Follett
Review Image by Melissa Follett Melissa Follett
Review Image by Melissa Follett Melissa Follett
Review Image by Melissa Follett Melissa Follett
I don’t think it is possible to get a better scope for the money. When my scope was delivered, I was amazed at the quality and features it had. Unfortunately, there was a defect in the scope where something was obstructing the view inside the opticals. I set up a return with Amazon and had a new scope delivered in 3 business days. I could have returned this scope and then bought a different one but I liked the look, the feel, the optics, the lighted reticles and the price. I also really like the lens covers as well. Mounting the scope was easy and the mounting hardware is excellent quality. This scope is perfect for my little .22 rifle and is easy to set up and sight in. The objective control and magnification controls are not the smoothest I have ever used, but the optics on this scope are quite simply amazing for the price. You really cannot go wrong with this scope! ... show more
Reviewed in the United States on June 6, 2023 by Melissa Follett Melissa Follett
    • Fantastic 10/22 optic
Style: Guardian | 4-12x50 AO
I bought this to replace the Viridian junk that came mounted on my 10/22. It's simply awesome. Great eye box, wonderful eye relief, and that big 50mm objective lets in a ton of light; so much so I haven't even needed the illumination at the range. I will say that there is a lot of light bleed at the higher settings of illumination, but as none is typically necessary, it's not a big deal at all. The throw lever is a bit stiff, but is starting to smooth out under use. The picture is clear at all magnifications, and the adjustable objective is a game changer. I've never used an AO scope before, MD this is just fantastic. Unlike the POS it replaced, I see a clear target instead of fuzzy mush. While I don't know if it'll hold up to larger calibers, for .22 it's fantastic. The price point is almost ridiculous for a scope like this. I would 200% buy it again. ... show more
Reviewed in the United States on January 8, 2023 by Amazonian Customerers
    • Solid scope for the price
Style: Guardian | 3-9x40 AO
For the price, this scope is a good value. The glass is clear, but the magnification adjuster is a little stiff but I am hoping it loosens up over time.
Reviewed in the United States on February 2, 2025 by MGS
    • Decent scope
Style: Guardian | 3-9x40 AO
Great scope, unfortunately it did not fit the rifle I bought it for,but that is not a reflection on the scope, but, I have another I can put it on. Or keep as a back hp.
Reviewed in the United States on February 26, 2025 by William
    • Good value
Style: Guardian | 3-9x40 AO
For a cheap scope option it's better than the rest. Highly suggest.
Reviewed in the United States on April 6, 2025 by Steven Harville
    • Sweet glass
Style: Guardian | 3-9x40 AO
Check most of the boxes after one takes into account it was $70.00 scope
Reviewed in the United States on February 16, 2025 by Shane Shier
    • MONSTRUM ALWAYS PROVIDES QUALITY AT AN EASILY AFFORDABLE PRICE!
Style: Guardian | 6-18x50 AO
My Monstrum Guardian Series AO Rifle Scope with Parallax Adjustment, is a Second Focal Plane scope (my preferred Focal Plane for long-range shooting [750yds+]). The glass is perfect (clear, sharp presentation of illuminated crosshairs, and no halo or fog), and the 1" tube is solid and well made. The 1/4 MOA/click windage and elevation adjustable turrets have screw-on covers to keep your adjustments secure once zeroed, and the clicks are smooth and positive. I have a couple of scopes costing 10 times more than the Monstrum Guardian Series AO Rifle Scope, and I bought it "just to check it out" because of the low-end price. I have used several Monstrum cantilever mounts, and other Monstrum products which impressed me enough to try their optics, and the Monstrum Guardian Series AO Rifle Scope with Parallax Adjustment surpassed my expectations. Monstrum provides an outstanding scope at a bargain price in the 6-18 power range. You are reading this review, and I have NO association with Monstrum other than as a customer, so if you're looking for a 6-18 variable optic, I STRONGLY recommend the Monstrum Guardian Series AO Rifle Scope! If you don't like it and bought it from Amazon, you can return it for credit or replacement. ... show more
Reviewed in the United States on December 5, 2023 by Gil
    • 2 for 2 Defective Scopes
Style: Guardian | 3-9x40 AO
Review Image by Audrey Jarmin Audrey Jarmin
I purchased this scope and initially received a defective product. The illumination turret would not turn at all no matter the pressure I applied and I was concerned that I would physically damage the scope. I processed a return and had them send me another scope. The second scope showed up and the illumination turret turned as it should. However, neither the green nor red illuminated on the fourth brightness setting. The illumination worked on all other setting levels, both green and red, but was inexcusably uneven across the reticle crosshairs. I’ve had reasonably good success with Monstrum’s scope rings, mounts, and other accessories, but in the future I will direct my purchasing dollars towards other manufacturers for better quality optics. ... show more
Reviewed in the United States on December 10, 2024 by Audrey Jarmin Audrey Jarmin

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