Search  for anything...
Monstrum

Monstrum Guardian Series AO Rifle Scope with Parallax Adjustment

    • Based on 1,033 reviews
Condition: New
Checking for product changes
$79.95 Why this price?

Buy Now, Pay Later

As low as $13.33 / mo
  • – 6-month term
  • – No impact on credit
  • – Instant approval decision
  • – Secure and straightforward checkout

Ready to go? Add this product to your cart and select a plan during checkout. Payment plans are offered through our trusted finance partners Klarna, PayTomorrow, Apple Pay, and PayPal. No-credit-needed leasing options through Acima may also be available at checkout.

Learn more about financing & leasing here.

Selected Option

Free shipping on this product

This item is eligible for return within 30 days of receipt

To qualify for a full refund, items must be returned in their original, unused condition. If an item is returned in a used, damaged, or materially different state, you may be granted a partial refund.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

Availability: In Stock.
Fulfilled by Amazon
Arrives Friday, May 10
Order within 6 hours and 35 minutes
Available payment plans shown during checkout

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


Item Package Dimensions L x W x H: ‎15.86 x 3.46 x 3.03 inches


Package Weight: ‎0.86 Kilograms


Brand Name: ‎Monstrum


Manufacturer: ‎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: Friday, 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.

  • Klarna Financing
  • Klarna Pay in 4
  • PayTomorrow Financing
  • Apple Pay Later
Leasing options through Acima may also be available during checkout.

Learn more about financing & leasing here.

Similar Products

Top Amazon Reviews

    • Best Optic For The Money...Period
Purchased a Ruger Precision .22lr to see if I liked the platform before I went with it for a 6.5 Creedmor. As the RPR .22 was only $350 I felt a little silly mounting a Burris or Leopold optic on a range toy. Saw the reviews on the Monstrom sights and figured for this price I would be getting an optic with lots of corners cut in build quality and components. It's cheaper than a box of good ammo so I really thought this would be on my rifle for one range trip then end up in my box'o'' old parts. Well I was surprised by the build quality. The tolerances on the tube, adjustment points, and even the mount felt and looked really good. Optic is a bit heavier than the specs but I will let that slide as it's a couple ounces. The glass that I thought would be super cheap with irregular appeture and poor clarity was pretty clear. This does not have the pristine image and sharp clarity of a Leupold's VX entry optic but you are paying $300 less. I have ZERO complaints about the quality and construction of this optic for less than $60 bucks. It exceeded my admittedly very low expectations by a wide margin. The reticule is also very basic and the manual did not provide adequate explanation of the mils appropriate caliber and load to provide what I think is a requirement for this style reticule. Don't think your getting a true FFP range finder finders on this glass. But, again it's a 50 dollar scope you shouldn't. The AO dial did allow a guesstimate of the distance to target by assessing the optical sharpness. It is a feature that you really should not see at this price point and it works. That is probably because the biggest surprise of this optic was the glass. It is not just adequate I would definitely say it is very good. The parallax adjustment was not spectacular but was comparable to what I would expect on a mid range Burris or Vortex. Bottom line it's good glass that allows for an adequate range calculation and provides a more than adequate visual acuity even at 9x. Again, I have seen better but this is the best glass and controls you will get for the money So I mounted this shockingly good quality optic to the Ruger and headed to the range. Mount was super easy, it's a picatinny if you can't figure it out you should not be playing with a firearm. So I started at 100 yards and was off paper the first shot at min magnification. Turned the elevation and windage dials one rotation unit each and missed again. Gave them a couple more twists and I was on paper. Took a couple shots to figure out the mils, which are set to I think 62 grain 5.56 or .223, definitely not a .22lr. I took a couple more shots from a full mount and got the feel for the reticule mils and the drop on the Hornady .22 I was firing. I pulled back to 50 yards and found zero in a 3 shots Pushed back out to 100 and was able to get a good zero after learning the system and adjustments. The Optic was a bit more than the round I was shooting should have so I put that on me underestimating the Scope. Windage and Elevation have nice firm click and resistance. Once you know what a rotational unit is going to do this optic is easy to zero. The Mag and AOcontrols worked well and the parallax was minimal. Eye relief was excellent. I was shooting a bolt action precision chasis rifle so recoil was almost non-existent. That said this optic easily held zero over probably 200 shots that day. The caps were ok more than I expected but the cheapest feeling component of the system. I have to say I was blown away that a scope with the quality and accuracy of this optic was in junk toy scope price range. Is it a $2,000 scope NOPE. It is comparable or better than many $300 - $500 dollar optics I've had from Burris and Vortex. Best damn scope I've ever used that was $50 bucks without a doubt. The Monstrum never went in the box'imparts it is still on the Ruger. Shoots great. For the money this is a no brainer and could easily be used with .223 or .270. I'm not sure how it would handle .308+; but it probably would hold a zero and be a great optic for hunting open terrain. I can't say this and mean it more, if your learning to distance shoot this is would be a great way to learn fundamentals. Without breaking the bank. A low end Rem 700 and this scope will leave you hundreds to spend on instruction and practice ammo. It exceeds all expectations and will give you a scope that feels and performs like one that is 6 times it's price. The best optic for your money period. Just don't put one on a Ruger Precision because that is a crack gun and gets you hooked fast and will quickly result in desire for one of his big brothers. I really loved the chasis and trigger and shockingly the optic. I have subsequently added a Alpha FFP1x6 24 to an AR race gun that my buddies all admitted shot as well as their $600+ FFP's. Beginning distance shooters can't go wrong with this high value optic you won't be out shooting your glass anytime soon. Seasoned shooters looking for a bargain or a practice rifle scope will be pleased as well. This optic changed my old rule the optic should be at least the cost of the rifle and double or triple if your going to 1,000+ shots. I can assure you this rifle can out to 200 yards with quality .22lr. It's the round not the optic that is limited the range and the optic was 1/8th the price of the gun. When I get the Ruger Precision in 6.5 I will likely give a G3 Monstrum the first crack at the picatinny rail. That will buy me a ton of rounds to enjoy the gun over the Leupold I would have been saving for months to buy. Fully recommended not just a good scope for the money but just a good scope period! ... show more
Reviewed in the United States on November 13, 2020 by Shannon Credle
    • Decent Rifle Optic
Style: Guardian | 6-18x50 AO
Trying to find an optic for a small caliber rifle, I stumbled upon this Monstrum Guardian 6-18x50, and decided to give it a go. About half the price of a Bushnell in the same zoom range. Included rings to mount it. Took it to the range, and I'm still not completely sold. Eye relief is decent, rings are very basic, but seem to hold. Optic caps are a nice touch, but get in the way for making focal adjustments (being they are flip ups). Not sure how to properly gauge it, but I'm doubting the 18x zoom is accurate. When compared to a vortex 12x, with 50mm objective lens, the zoom appears almost less. Still a functional small caliber option, just don't believe the zoom rating. ... show more
Reviewed in the United States on July 14, 2023 by B. Peterson
    • Good choice for the money.
Style: Guardian | 3-9x40 AO
This scope is exactly what was described to be. It is a very accurate, I'm shooting out to distances of 100 yards with my 177 cal. Break barrel rifle. The only thing wrong is the green back lit cross hair don't work. That's not a deal breaker for me.
Reviewed in the United States on August 5, 2023 by Victor LaFata Jr.
    • Pleasantly surprised!
Style: Guardian | 6-18x50 AO
Did not expect so much for so little,, very good set up for my Bobcats.
Reviewed in the United States on August 30, 2023 by Robert
    • Mounted
Style: Guardian | 3-9x40 AO
Item was received as scheduled. Mounted easy, but yet to use.
Reviewed in the United States on August 2, 2023 by Gary R
    • 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
    • Good Value
Style: Guardian | 3-9x50 AO
Clear optics, works well as described. A very good scope for the price range. Recommended.
Reviewed in the United States on August 14, 2023 by J.D.
    • Best for money
Style: Guardian | 3-9x50 AO
Works great for me shooting within 100 yards with a .22
Reviewed in the United States on August 17, 2023 by Parkracer

Can't find a product?

Find it on Amazon first, then paste the link below.