Nikko Stirling MountMaster AO 3–9×40 NMM3940AON – HMD, 3/8″ Mounts
Nikko Stirling MountMaster AO 3–9×40 NMM3940AON – HMD, 3/8″ Mounts
- Brand:NIKKO STIRLING
- Product Code: MountMaster AO 3–9×40 NMM3940AON – HMD, монтаж
- Availability: In Stock
68.00 € / 133.00 лв.
88.00 € / 172.11 лв.07 11 2026 06 12 2026
Classic 3–9× magnification, adjustable parallax from 9.1 m and a practical Half Mil Dot reticle. The Nikko Stirling MountMaster AO 3–9×40 is a versatile daytime riflescope for users who appreciate straightforward mechanical controls, clear optical performance and the ability to focus at different observation distances.
Its compact design features a 1-inch main tube, a 40 mm objective and included 3/8″ mounting rings for compatible air rifles and rimfire platforms. The HMD reticle has no electronic illumination, making its etched markings visible without a battery.
Nikko Stirling MountMaster AO 3–9×40 · product code NMM3940AON
Nikko Stirling MountMaster AO 3–9×40 Half Mil Dot combines three particularly useful features: proven 3–9× variable magnification, a 40 mm objective and front-mounted adjustable parallax control.
At 3×, the scope provides a broader overview of the observed area. At 9×, smaller details appear larger, accompanied by a narrower field of view. This makes it a balanced configuration for compatible air rifles, training and lawful sporting applications.
AO (Adjustable Objective) provides parallax focusing from approximately 9.1 metres to infinity. Unlike optics with a fixed factory parallax setting, this model allows users to adjust the focus of the observed image for different distances.
The body has a matte black finish, with Multicoated optical surfaces designed to reduce reflections. Nitrogen filling and protective construction provide resistance to water, internal fogging and shocks.
Choose a wider field of view at 3× or a more detailed image at 9× without changing the optic.
The front adjustment ring allows focus to be adapted to different observation distances.
Additional angular reference marks provide useful visual information for comparisons and training.
A practical combination of optical capability, dimensions and ease of use.
Anti-reflective treatment supports image clarity and contrast.
A nominal adjustment step of approximately 7 mm at 100 m per click.
Factory-provided 3/8″ dovetail mounting rings for compatible rails.
Nitrogen filling, waterproof design, shock resistance and fog protection.
The 3–9× magnification range offers a threefold ratio between minimum and maximum magnification. It provides useful flexibility without unnecessary operating complexity.
The important additional feature is the adjustable objective (AO). It enables the image to be focused for nearer or more distant objects rather than remaining at a single factory-set parallax distance.
The Half Mil Dot reticle adds angular reference marks, while the standard 1-inch tube maintains compatibility with a widely used mounting format.
Adjustable Objective refers to a focusing and parallax control positioned around the front objective assembly of the MountMaster AO 3–9×40.
Turning the AO ring changes the optical focus according to observation distance. When the image and reticle are aligned within the optical system, the apparent movement of the reticle relative to the subject, caused by small changes in eye position, is reduced.
Look briefly at a bright, neutral background and adjust the eyepiece until the reticle appears sharp.
Select a comfortable level according to the required field of view and image detail.
Turn the AO ring towards the appropriate distance and bring the observed subject into focus.
With the optic stationary, check that apparent reticle movement is minimal as your eye changes position slightly.
Half Mil Dot is a reticle concept using angular references expressed in milliradians. One milliradian corresponds to approximately 1 metre at a distance of 1,000 metres; half a mil represents half that angle.
These reference marks can help experienced users compare the apparent angular dimensions of different objects. Rather than a plain crosshair, HMD provides additional visual information for sporting and training applications.
- Mil: an angular unit different from MOA.
- Half Mil: half a milliradian.
- Reference marks: visual guides for angular comparison.
- Turret adjustments: expressed in MOA, a different system from the reticle's mil units.
When interpreting angular reticle marks, consider the magnification at which their nominal subtensions apply. Refer to the specific model instructions for calibration information.
Field of View (FOV) means the width of the area visible through a scope at a given distance. With the MountMaster AO 3–9×40, this changes noticeably between the lowest and highest magnification.
At low magnification, you can observe more of the surrounding area. At higher magnification, individual details appear larger while the visible sector becomes narrower.
The Multicoated optical treatment helps reduce unwanted reflections at glass surfaces and supports useful light transmission and image contrast.
The 40 mm objective offers a sensible balance between physical size and optical capability. Together with 3–9× variable magnification, it forms a practical combination for a variety of daytime observation conditions.
The MountMaster AO features adjustment turrets with a nominal 1/4 MOA click value. MOA stands for *Minute of Angle*, an angular unit commonly used for riflescope adjustments.
A single 1/4 MOA click corresponds to approximately 7 mm at 100 metres. The stated 60 MOA range for each axis describes mechanical adjustment travel rather than the guaranteed accuracy of any particular system.
One practical advantage of the NMM3940AON package is its included 3/8″ dovetail mounting rings. These are intended for compatible dovetail rails.
This mounting format is sometimes described as an 11 mm-style dovetail interface. Actual compatibility, however, depends on the rail profile and the rings' clamping range.
The scope uses a 1-inch tube and is not designed to fit standard 30 mm rings.
The included mounts are designed for dovetail rails and are not universal Picatinny rings.
AO adjustment, a 1-inch tube and dovetail mounts are useful for suitably matched air rifles. Spring-powered models require separate verification of recoil compatibility.
The 3–9× range and Half Mil Dot reticle offer useful features for lawful sporting and training applications.
This model provides an accessible way to learn the difference between eyepiece focus, parallax adjustment and turret corrections.
Variable magnification, a 40 mm objective and AO focusing offer practical flexibility during daytime observation.
For comfortable use and long service life, pay attention to correct adjustment, compatible mounting and regular optical care.
Before technical inspection or mounting on a firearm, verify that it is unloaded and follow all applicable safe-handling procedures.
Look briefly at a bright, neutral background and adjust the eyepiece until the reticle is sharp. Never point the scope towards the sun.
Use 3× for a wider field of view and gradually increase towards 9× when you need more image detail.
Adjust the front parallax ring to the observation distance. Fine-tune it as necessary to achieve a clear image.
Confirm mounting compatibility and correct positioning. Follow tightening instructions and avoid excessive force.
Remove dust and grit using a soft brush before wiping. Use clean cloths and cleaning solutions suitable for optical surfaces.
Despite the waterproof construction, dry the scope after use in wet conditions and avoid storing it while damp.
Fit protective lens caps and keep the scope in a dry location away from excessive heat, impacts and abrasive materials.
| Specification | Details |
|---|---|
| Manufacturer | Nikko Stirling |
| Series | MountMaster |
| Model | MountMaster 3–9×40 AO |
| Product code | NMM3940AON |
| Type | Daytime riflescope |
| Magnification | 3–9× |
| Objective diameter | 40 mm |
| Main tube | 1″ / 25.4 mm |
| Field of view at 3× | 11.9 m at 100 m |
| Field of view at 9× | 4.0 m at 100 m |
| Reticle | HMD / Half Mil Dot |
| Electronic illumination | No |
| Optical coatings | Multicoated |
| Parallax adjustment | AO / Adjustable Objective |
| AO focus range | 9.1 m to infinity |
| Click value | 1/4 MOA / approx. 7 mm at 100 m |
| Elevation range | 60 MOA |
| Windage range | 60 MOA |
| Eye relief | 85 mm |
| Eyepiece adjustment | Fast Eye Focus |
| Overall length | 322 mm |
| Weight | 380 g |
| Main tube material and finish | Metal alloy, matte black finish |
| Nitrogen-filled | Yes |
| Waterproof | Yes |
| Internal fog protection | Yes |
| Shockproof | Yes |
| Mounting system | 3/8″ dovetail rings included |
| Intended use | Compatible airgun and rimfire platforms |
- Nikko Stirling MountMaster AO 3–9×40 HMD riflescope, product code NMM3940AON.
- 3/8″ mounting rings for a compatible dovetail rail.
- Factory accessories and accompanying materials according to the original package supplied.
Check compatibility of the supplied mounting rings with your equipment before installation. The MoskovHunt team can assist with selecting another mounting system when required.
Nikko Stirling riflescopes are covered by a lifetime manufacturer's warranty programme for the original owner, subject to the brand's applicable conditions.
- Product registration is required to benefit from the manufacturer's programme.
- Proof of original purchase may be requested.
- Improper use, misuse and unauthorised repairs are excluded.
- For a valid claim, the manufacturer may repair or replace the product under the programme terms.
The manufacturer's warranty programme does not restrict statutory consumer rights.
Selected MoskovHunt products may be eligible for TBI Bank instalment financing when the particular item meets the financing conditions and the option is active.
Credit availability, repayment periods, monthly instalments, interest rates, APR and total payable amounts depend on the bank's offer and individual approval. Special promotional financing programmes are not automatically combinable with product discounts.
NMM3940AON – Nikko Stirling MountMaster AO 3–9×40 with Half Mil Dot reticle.
Adjustable Objective – front-mounted parallax adjustment from 9.1 m to infinity.
No. This version uses a non-illuminated HMD reticle. The illuminated model is a separate version.
A reticle with angular reference marks in milliradians, including half-mil references, used for visual comparisons.
11.9 m at 3× and 4.0 m at 9× magnification.
1/4 MOA, approximately 7 mm at 100 m.
380 g, with an overall length of 322 mm.
1 inch, equivalent to 25.4 mm.
Yes, 3/8″ dovetail mounting rings for a compatible rail.
Not directly. The supplied mounts are for a dovetail rail. Picatinny requires another compatible mounting solution.
Yes, provided it is compatible with the specific action, rail and recoil characteristics. Check spring-powered models separately.
Yes, using the Fast Eye Focus ring on the eyepiece.
A lifetime manufacturer's programme, subject to registration and Nikko Stirling's warranty conditions.
Get professional assistance with NMM3940AON, the Half Mil Dot reticle, AO focusing, the supplied 3/8″ rings and compatibility with your equipment.
MoskovHunt · 37 Tsar Simeon Street, 5900 Levski, Bulgaria.
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