Nikko Stirling Mountmaster 6x40 AO

• Fixed 6x magnification: A simple fixed-power layout keeps the sight picture consistent and uncluttered, which helps with quick target acquisition and repeatable holdover on rimfire rifles and general hunting setups.
• Adjustable objective parallax: The front objective adjusts from 9.1 m to infinity, letting the scope stay sharp at short and longer distances while reducing aiming error when shooting at varying ranges.
• HMD reticle in second focal plane: The HMD reticle keeps the same apparent size across use, giving a familiar aiming reference that is easy to see against small game and range targets.
• 1 inch alloy tube with capped turrets: The 25.4 mm tube and capped adjustment system keep the scope light and tidy, while protecting zero from accidental movement during transport or field carry.
• Multicoated, nitrogen-filled construction: Multicoated lenses support a clear image, while the waterproof, fogproof and shockproof build helps the scope stay usable in damp weather and regular hunting use.

About the Mountmaster Series

The Nikko Stirling Mountmaster series sits in the brand's accessible hunting optics range, built for shooters who want a straightforward riflescope with practical field features rather than a complex tactical layout. Across the series, the emphasis is on simple operation, compact dimensions and dependable mechanical design for rimfire rifles, air rifles and general-purpose sporting rifles. The line includes fixed-power and variable-power models, with options for adjustable objective parallax and illuminated reticles on selected versions.

What defines the series is its focus on useful essentials: fully multicoated lenses, a 1 inch tube, finger-adjustable turrets and a dry-nitrogen-purged body that is waterproof and fogproof. Reticle choices such as the HMD pattern are intended for clear aiming without an overly busy sight picture, which suits hunting and informal target work. The Mountmaster approach is practical rather than specialized, giving shooters a scope family that covers common sporting applications with familiar controls, moderate weight and optical layouts that are easy to live with in the field.

About the Nikko Stirling Mountmaster 6x40 AO

The Nikko Stirling Mountmaster 6x40 AO is a fixed-power riflescope designed for shooters who prefer a consistent sight picture and uncomplicated handling. Its 6x magnification gives more target detail than a low-power hunting scope while avoiding the extra weight and moving parts of a variable design. That makes it a sensible fit for rimfire shooting, small-game hunting and general range use, where repeatability and ease of use often matter more than frequent magnification changes.

The 40 mm objective lens balances brightness and manageable size, while the multicoated optics help preserve contrast and image clarity in mixed light. A field of view of 7.30 m/100m keeps enough surrounding detail visible for practical hunting distances, and the 85.00 mm eye relief supports a comfortable head position behind the rifle. The adjustable objective is one of this model's key advantages: by focusing parallax from 9.1 m to infinity, it works well for close rimfire distances as well as longer shots where image sharpness and aiming precision become more important.

The HMD reticle sits in the second focal plane, so its apparent size remains constant and familiar to the eye. Combined with capped 1/4 MOA turrets, this setup favors a hunting-style workflow: set the zero, protect the adjustments, and rely on a clean reticle for day-to-day shooting. The 1 inch tube, 323.00 mm length and 325.00 g weight keep the scope easy to mount on lighter rifles, while the waterproof, fogproof, shockproof and nitrogen-filled construction supports regular outdoor use.

About Nikko Stirling

Nikko Stirling traces its inception to 1956, when it was established by Malcolm John Fuller. The brand focuses on sport optics for hunters and marksmen, with a product range that covers riflescopes, reflex sights, binoculars and laser rangefinders. Within its riflescope lineup, families such as Diamond Hunting, Diamond FFP, Metor, Panamax, Airking and Mountmaster show the brand's broad coverage of hunting and shooting applications, from straightforward sporting scopes to more specialized configurations.

Beyond riflescopes, Nikko Stirling also offers Metor HD binoculars and NSLRF laser rangefinders, reflecting a long-standing concentration on field and shooting optics rather than a general outdoor catalog. That specialization is relevant here, because the Mountmaster series follows the same practical design approach the brand is known for: clear function, familiar controls and optics intended for real hunting and range use.

Main Features

• Magnification: 6.00 x
• Objective lens diameter: 40.00 mm
• Main tube diameter: 25.4 mm
• Reticle: HMD
• Reticle position: 2. focal plane - SFP
• Illumination: No
• Click value: 7mm/100m - 1/4MOA
• Turret type: Capped
• Elevation adjustment: 8.72 mrad / 30.00 MOA
• Windage adjustment: 8.72 mrad / 30.00 MOA
• Eye relief: 85.00 mm
• Field of view: 7.30 m/100m
• Parallax adjustment: Yes - objective
• Parallax adjustment range: 9.1 m to infinity
• Lens coatings: Multicoated
• Length: 323.00 mm
• Weight: 325.00 g
• Nitrogen filled: Yes
• Waterproof: Yes
• Fogproof: Yes
• Shockproof: Yes
• Color: Black
• Made in: China

Warranty

2 years. Nikko Stirling states a 2-year warranty for this riflescope.

In the Box

• 3/8” mount