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You are here: Home / Rifle Scopes / Monstrum 3-9×40 Rifle Scope with AO Adjustable Objective | with Ruger 10/22 Dual Ring Scope Mount
Monstrum Rifle Scope 1 Monstrum 3-9x40 Rifle Scope with AO Adjustable Objective | with Ruger 10/22 Dual Ring Scope Mount
Monstrum Rifle Scope 2 Monstrum 3-9x40 Rifle Scope with AO Adjustable Objective | with Ruger 10/22 Dual Ring Scope Mount
Monstrum Rifle Scope 3 Monstrum 3-9x40 Rifle Scope with AO Adjustable Objective | with Ruger 10/22 Dual Ring Scope Mount
Monstrum Rifle Scope 4 Monstrum 3-9x40 Rifle Scope with AO Adjustable Objective | with Ruger 10/22 Dual Ring Scope Mount
Monstrum Rifle Scope 5 Monstrum 3-9x40 Rifle Scope with AO Adjustable Objective | with Ruger 10/22 Dual Ring Scope Mount

Monstrum 3-9×40 Rifle Scope with AO Adjustable Objective | with Ruger 10/22 Dual Ring Scope Mount

Was $59.95 - check current price

Check Out Monstrum 3-9×40 Rifle Scope with AO Adjustable Objective | with Ruger 10/22 Dual Ring Scope Mount. See Great Rifle Scopes By Monstrum.

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SKU: 254cb7fb94b4 Category: Rifle Scopes Tag: rifle scope
  • Description
  • Additional information

Description

Rifle Scope Product Details

Monstrum 3-9×40 Rifle Scope with AO Adjustable Objective | with Ruger 10/22 Dual Ring Scope Mount

Rifle Scope Product Features

End-to-end rifle scope solution built exclusively Ruger 10/22 platform
Adjustable 3-9 times magnification, for targeting out to 500 yards and beyond
An adjustable objective lens or AO – that allows for sharper focus of the target image, elimination of parallax, and range estimation
Scope mount installs directly to the Ruger 10/22 receiver via the factory mounting holes and included set screws with no additional hardware required
Precision machined from 6061 grade aluminum, comparable in weight to most scope rings with the added rigidity of a unified one piece mount design
Technical Specifications
Magnification: 3-9x
Objective Diameter: 40 mm
Length: 11.75 in
Weight: 15 oz
Eye Relief: 3.0 -3.5 in
Tube Diameter: 1 in
Shock Water and Fog Proof Yes. Nitrogen Sealed.
Scope Range: Mid Range. Up to 500 Yards.
Included: 3-9×40 AO Scope, RUG-01 Ruger 10/22 Mount, CR2032 Battery, Manual
Compatibility: Fits All Ruger 10/22 Models: Takedown, Carbine, Target, Compact, Sporter, Collector’s, Tactical, and 50th Anniversary.
The Monstrum S3940-AO-B Ruger Edition is the first end-to-end rifle scope solution built exclusively for America’s most beloved 22 rifle. With crystal clear optics, variable magnification from 3-9x, and a dedicated one-piece scope mount custom designed for the Ruger 10/22 platform, the S3940-AO-B Ruger Edition provides everything for taking your Ruger 10/22 to the next level.
The scope comes equipped with:
Adjustable 3-9 times magnification, for targeting out to 500 yards and beyond
1/4 MOA/click windage and elevation adjustment dials with locking turrets
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 construction, for lightweight and durable performance
A detachable throw lever for smooth and controlled adjustment of the magnification dial.
A sealed, nitrogen charged scope tube for resistance to fog and water.
Precision machined from 6061 grade aluminum, the scope mount is the most rigid, lightweight, and easy to install Ruger 10/22 mounting solution on the market. The scope mount base installs directly to the Ruger 10/22 factory mounting holes via the included set screws. No additional mounting hardware is required.
The rings are 1 inch in diameter for precision mounting of standard 1 inch tube rifle scopes. They provide 0.7 inches of height, measured from the base of the mount to the bottom of the scope tube. The mount weighs a mere 3 ounces, comparable to most scope rings but with the added rigidity of a unified one piece mount.
Monstrum Ruger 10/22 Picatinny Rail Monstrum Ruger 10/22 2-Piece Picatinny Rail Monstrum Ruger 10/22 1″ Scope Rings Monstrum Ruger 10/22 3-9×40 AO Rifle Scope and Mount
# of Slots 11 5 0 N/A
Length: 4.63 in 2.50 in 2.25 in N/A
Width: 0.88 in 0.88 in 0.88 in N/A
Weight: 1.3 oz 0.7 oz 3.0 oz 18 oz
6061 Aircraft Grade Aluminum:
Heat-Treated Screws:
Stock Sights Usable When Optic Removed
Stock Sight Usable When Optic Still On

About the Monstrum Manufacturer

Monstrum is a premium supplier for long gun scopes, optics, mounts, and other add-ons used for firearms like rifles and long guns. They create and build their mounts and related products by choosing building materials which are durable and long lasting. This includes the Monstrum 3-9×40 Rifle Scope with AO Adjustable Objective | with Ruger 10/22 Dual Ring Scope Mount by Monstrum. For more shooting items, visit their site.

What You Need to Know About Rifle Optics

Rifle scopes enable you to exactly aim a rifle at various targets by aligning your eye with the target at range. They accomplish this through magnification using a series of lenses inside the scope. The scope’s alignment can be adjusted for the consideration of various natural elements like wind speed and elevation decreases to make up for bullet drop.

The scope’s function is to help shooters understand exactly where the bullet will hit based upon the sight picture you are viewing using the optic as you align the scope’s crosshair or reticle with the target. Most modern rifle scopes and optics have about eleven parts which are arranged within and externally on the scope. These parts include the rifle scope’s body, lenses, windage dials or turrets, focus rings, and other elements. See all eleven parts of a rifle scope.

The Styles of Rifle Scopes

Rifle scopes can be either “first focal plane” or “second focal plane” type of optics. Going for the finest type of rifle optic is based around what type of shooting you plan on doing.

Info on First Focal Plane Optics

Focal plane scopes (FFP) feature the reticle in front of the zoom lens. These styles of scopes are useful for:

  • Quick acquisition, far away kinds of shooting
  • Shooting situations where computations are minimal
  • Experienced shooters who understand their aim point “hold over” and “lead” ratios for their long guns
  • Shooters who don’t mind the reticle is enlarged and occupies more visual sight area than a SFP reticle

About Second Focal Plane Glass

Second focal plane optics (SFP) feature the reticle to the rear of the magnification lens. In the FFP example with the SFP scope, the 5x “zoom” one hundred yard tick would be 1/5th of the non “zoom” tick.

  • Long distance kinds of shooting where shooters have increased time to make ballistic estimations
  • Shooting where most shots occur within much shorter ranges and distances
  • Shooters who prefer a clearer optic sight picture without area taken up by the bigger FFP reticle

Zoom for Glass

The level of scope magnification you need on your glass is based on the form of shooting you plan to do. Pretty much every style of rifle scope provides some degree of magnification. The volume of magnification a scope supplies is determined by the diameter, density, and curvatures of the lens glass inside of the rifle scope. The zoom of the scope is the “power” of the glass. This suggests what the shooter is observing through the scope is magnified times the power aspect of what can typically be seen by human eyes.

Fixed Power Lens Rifle Scope Info

A single power rifle optic and scope uses a zoom number designator like 4×32. This suggests the zoom power of the scope is 4x power and the objective lens is 32mm. The magnification of this kind of optic can not change considering that it is a fixed power optic.

Info on Variable Power Lens Glass

Variable power rifle scopes have adjustable power. These types of scopes will list the magnification degree in a format such as 2-10×32. These numbers indicate the magnification of the scope could be changed between 2x and 10x power. This also involves the power levels in-between 2 and 10. The power shift is accomplished by making use of the power ring component of the scope near the back of the scope by the eye bell.

The Power and Range Correlation of Rifle Glass

Here are some advised scope powers and the distances where they can be successfully used. Consider that high power scopes and optics will not be as practical as lower powered scope and optics since increased magnification can be a detractor. The same concept applies to longer distances where the shooter needs to have sufficient power to see precisely where to properly aim the rifle at the target.

Lens Covering for Scopes

All contemporary rifle scope and optic lenses are covered in special coatings. There are different types and qualities of coverings. When looking at high end rifle optics and scope systems, Lens finish can be a crucial component of a rifle. The glass lenses are among the most important pieces of the optic due to the fact that they are what your eye looks through while sighting a rifle in on the target. The finishing on the lenses shields the lens surface and even helps with anti glare capabilities from refracted daylight and color perception.

HD Versus ED Lens Coatings

Some scope producers likewise use “HD” or high-definition lens coverings which use various procedures, elements, chemicals, and polarizations to draw out separate colors and viewable quality through the lens. Some scope manufacturers use “HD” to refer to “ED” implying extra-low dispersion glass.

Single Finish Versus Multi-Coating

Different optic lenses can likewise have different finishes used to them. All lenses generally have at least some type of treatment or finishing applied to them before being used in a rifle scope or optic.

Single coated lenses have a treatment applied to them which is usually a protective and enhancing multi-purpose treatment. This lens treatment can preserve the lens from scratches while minimizing glare and other less advantageous things experienced in the shooting environment while sighting in with the optic. The quality of a single covered lens depends upon the scope designer and just how much you spent on it. Both the make and cost are indicators of the lens quality.

Some scope manufacturers likewise make it a point to specify if their optic lenses are coated or “multi” covered. This suggests the lens has several treatments applied to the surfaces of the glass. If a lens gets numerous treatments, it can show that a producer is taking numerous actions to fight different environmental factors like an anti-glare finish, a scratch resistant anti-abrasion finishing, followed by a hydrophilic finish. This additionally does not necessarily mean the multi-coated lens is better than a single covered lens. Being “much better” hinges on the manufacturer’s lens treatment techniques and the quality of components used in constructing the rifle scope.

Anti-water Rifle Scope Lens Covering

Water on a lens doesn’t assist with maintaining a clear sight picture through a scope at all. Numerous top of the line and high-end optic companies will coat their lenses with a hydrophobic or hydrophilic finishing.

Optic Installation Alternatives

Installing solutions for scopes are available in a few options. There are the standard scope rings which are separately mounted to the scope and one-piece mounts which cradle the scope. These various types of mounts also normally can be found in quick release variations which use throw levers which allow rifle operators to rapidly install and dismount the scope.

Rifle Optic Mounts with Hex Key Rings

Standard, clamp design mounting scope rings use hex head screws to mount to the flattop style Picatinny scope mount rails on rifles. These types of scope mounts use a couple of different rings to support the optic, and are made from 7075 T6 billet aluminum which is developed for long distance accuracy shooting. This type of scope install is wonderful for rifles which require a long lasting, sound mounting solution which will not move no matter how much the scope is moved or abused.

Rifle Glass Mounting Solutions with Quick-Release Cantilever Rings

These types of quick-release rifle scope mounts can be used to rapidly attach and detach a scope from a rifle before reattaching it to a different rifle. Numerous scopes can also be switched out if they all use a compatible style mount. These types of mounts are handy for rifles which are carried a lot, to remove the optic from the rifle for protecting the scope, or for scopes which are used in between numerous rifles.

Rifle Optic Tube Sealing and Gas Purging

Moisture inside your rifle optic can wreck a day of shooting and your highly-priced optic by inducing fogging and producing residue inside of the scope’s tube. Many scopes protect against humidity from getting in the optical tube with a series of sealing O-rings which are water resistant. Generally, these water resistant scopes can be immersed under 20 or 30 feet of water before the water pressure can push moisture past the O-rings. This should be ample moisture content avoidance for conventional use rifles for hunting and sporting purposes, unless you anticipate taking your rifle boating and are worried about the scope still performing if it is submerged in water and you can still recover the gun.

Scope Gas Purging

Another part of preventing the buildup of wetness inside of the rifle optic’s tube is filling the tube with a gas like nitrogen. Because this area is currently occupied by the gas, the glass is less influenced by condition alterations and pressure distinctions from the external environment which may potentially enable water vapor to permeate in around the seals to fill the void which would otherwise exist. These are good qualities of a good rifle scope to look for.

Additional information

Category

Rifle Scopes

Brand

Monstrum

ASIN

B08LXS7Y2M

Reviews

Over 5

Reviews Rating

4.7 out of 5 stars

Prime

Amazon Prime

Shipping

FREE Shipping by Amazon

Best Sellers

Last update on August 19, 2026 // Source: Amazon API

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