Air Arms S400 Biathlon

The Air Arms S400 Biathlon air rifle is a refined precision tool designed for competitors, enthusiasts, and serious target shooters alike. As a pre-charged pneumatic (PCP) rifle, it offers a modern power system that delivers clean, consistent shots, making it especially suited for sustained training sessions and high-precision shooting disciplines.

Air Arms S400 Review || Air Arms S400 Problems

Designed for durability, the S400 Biathlon features an integrated manometer (pressure gauge) that allows you to effortlessly keep track of your air reservoir.

The streamlined design simplifies the internal mechanism, leading to lower maintenance requirements and enhanced reliability.

Users need to adhere to the manufacturer’s guidelines regarding filling, cleaning, and maintenance. The manual recommends letting the reservoir pressure decrease before unscrewing it for a refill, as this practice helps to minimize wear.

Pros & Considerations

Pros:

• Exceptional accuracy and repeatability thanks to match-grade components.

• Good shot count per fill with 200-bar PCP system.

• Highly adjustable ergonomic stock.

• Customizable trigger and sight options.

• Durable and low-maintenance due to unregulated design.

Considerations:

• As a Precision PCP Competition Rifle, you’ll need a suitable high-pressure fill source (tank, compressor, or adapter).

• The rifle is tuned for precision rather than raw power — it’s not a high-energy hunting monster.

• Diopter rear sight may need to be purchased separately.

Features

• Precharged pneumatic (PCP)
• (200 bar max fill pressure)
• Bolt-action 5-shot repeater (self-indexing rotary clip)
• Removable air reservoir
• Match sights: globe front accepts inserts, rear diopter (not included)
• 11mm dovetail
• 5-way adjustable match trigger
• Lothar Walther barrel
• White poplar stock
• Cheekpiece adjusts vertically and horizontally
• Buttpad adjusts vertically, 4 rotary clips fit in slots in the right-hand forearm
• Beautiful deep bluing
• Stock is flawlessly executed
• 29.875″ between front & rear sight positions 10.25″ long accessory rail 12.12″ to 12.50″ length of pull (LOP) 5.15 ft-lbs.
• Includes owner’s manual, 7 Allen keys, four 5-shot clips, fill adapter & spanner (to remove reservoir)

Rear Diopter sight not included

Air Arms S400 Biathlon Air Rifle

The Air Arms S400 Biathlon is a precision-engineered pre-charged pneumatic (PCP) air rifle that’s ideal for competitive shooting and biathlon-style disciplines. Built with British craftsmanship, it features a .177 (4.5 mm) caliber barrel, a five-shot self-indexing rotary clip, and a smooth bolt-action mechanism. With a max velocity of 564 fps and muzzle energy of 5.15 ft-lbs, it delivers consistent, repeatable shots.

The rifle’s Lothar Walther match-grade barrel ensures outstanding accuracy, while the five-way adjustable match trigger provides a refined, customized pull. The white poplar stock offers both elegance and ergonomic comfort, with cheekpiece and buttpad adjustable to the shooter’s preference. It also has an 11 mm dovetail rail for adding optics, and comes with an owner’s manual, fill adapter, four rotary clips, and more. Whether for target competition or precision training, the S400 Biathlon combines reliability, balance, and performance in a beautifully finished package.

Manufactured by Air Arms, a well-respected British airgun company, the S400 Biathlon is part of the larger S400 family, celebrated for its simplicity, durability, and accuracy. The rifle reflects decades of engineering refinement: the bolt-action system is smooth and reliable, and its single-shot or repeater functionality (via the five-shot self-indexing rotary clip) allows for disciplined, repeatable shooting.

Who Is It For?

The S400 Biathlon is ideal for:

• Competition shooters: Its consistent shot-to-shot performance, accurate barrel, and high-quality trigger make it a favorite for target disciplines.

• Biathlon or field-target training: The ergonomics and repeatability support disciplined, high-precision shooting.

• Serious hobbyists: Even outside competition contexts, this rifle is a joy for anyone who appreciates precision airguns.

Its design encourages good shooting technique: whether in prone, standing, or supported positions, the adjustable stock helps get a solid, repeatable hold.