✅ Gas Ram Power Plants for Air Rifles – Custom Solutions for OEM & Brands

50,000+ Cycle Durability

Tested for over 50,000 compression cycles, ensuring reliable durability and consistent long-term performance.

Custom Stroke & Pressure

Available in 60–120mm stroke lengths with customizable 35–65lbs pressure ratings for precise specifications.

Wide Air Rifle Compatibility

Compatible with popular brands including Gamo, Hatsan, Crosman, Diana, Stoeger, and Weihrauch.

GASTAC is a professional manufacturer specializing in gas ram power plants for air rifles. With years of experience in precision engineering and gas spring technology, we provide OEM and ODM gas ram solutions for airgun brands worldwide. GASTAC gas piston units are designed to replace traditional coil springs, offering superior longevity, consistent power output, and enhanced shooting performance. As an ISO-certified supplier, we deliver reliable, high-performance gas ram systems tailored to your specific rifle models.

What Is a Gas Ram in an Air Rifle?

An air rifle gas ram is a sealed pneumatic power component designed to replace the conventional coil spring in a spring-powered air rifle. Instead of relying on a metal spring, the system uses compressed gas to store energy and drive the piston during the firing cycle.

Gas rams are also commonly referred to as gas pistons, gas springs, or nitro pistons, depending on the manufacturer and market.

Compared with traditional coil-spring systems, a gas ram provides a different power plant configuration with a smooth operating cycle, consistent performance, and reduced dependence on a conventional metal spring.

How Does an Air Rifle Gas Ram Work?

The gas ram stores energy through compressed gas inside a sealed cylinder. During the cocking process, the gas ram is compressed and stores potential energy. When the trigger is released, the gas ram extends rapidly and drives the piston forward, compressing the air inside the compression chamber and generating the propulsion required to fire the pellet. This operating principle allows the gas ram to function as the power plant of a spring-powered air rifle.

  • Cocking: The gas ram is compressed, storing energy in the sealed system.

  • Trigger Release: The trigger mechanism releases the piston assembly.
  • Gas Ram Extension: The compressed gas drives the piston forward.
  • Air Compression: The piston compresses air inside the compression chamber.
  • Pellet Propulsion: The compressed air propels the pellet through the barrel.

Standard Size Series – How to Select the Right Series

Gas rams are classified based on the combination of piston rod and tube diameters and identified by a two-digit code, such as 6-15 (6 mm piston rod, 15 mm tube diameter). Each series offers distinct features suited to specific load and space requirements. The table below outlines all standard series, showing the dimensions and force values ​​for each.

6-15 Series Gas Ram Size Chart

Product CodeRod Diameter (mm)Tube Diameter (mm)Stroke (mm)Extended Length (mm)Force Range (N)
6150401502506154015050 – 250
6150602002506156020050 – 250
6150802552506158025550 – 250
61510029525061510029550 – 250
61512034025061512034050 – 250

8-18 Series Gas Ram Size Chart

Product CodeRod Diameter (mm)Tube Diameter (mm)Stroke (mm)Extended Length (mm)Force Range (N)
818100280600818100280100 – 600
818120320600818120320100 – 600
818150380600818150380100 – 600
818200480600818200480100 – 600
818250590600818250590100 – 600
818300720600818300720100 – 600

10-22 Series Gas Ram Size Chart

Product CodeRod Diameter (mm)Tube Diameter (mm)Stroke (mm)Extended Length (mm)Force Range (N)
10220802451100102280245100 – 1100
102210030011001022100300100 – 1100
102215041511001022150415100 – 1100
102220052511001022200525100 – 1100
102225063011001022250630100 – 1100
102230076011001022300760100 – 1100

Gas Ram vs. Coil Spring

Both gas ram and spring piston air rifles are self‑contained mechanical systems that require no external charging equipment. The key difference lies in how each system stores and releases energy. Below is a detailed comparison:

Comparison DimensionGas Ram (Gas Spring)Steel Spring (Coiled)
Energy StorageCompressed nitrogen gas in a sealed cylinderCompressed coiled steel spring
LifespanDecades; gas springs do not fatigue like metalApproximately 10 years; spring fatigue and breakage
Can Be Left CockedCan remain cocked for extended periods without power lossLoses power over time when left cocked
Shot CycleSmoother impulse with minimal "twang" and vibrationNoticeable vibration and spring noise
Lock TimeVery fast, measured in millisecondsSlower lock time
RecoilSmoother recoil with reduced rotational componentMore pronounced recoil with rotational element
WeightLighter than equivalent spring systemsHeavier
MaintenanceRequires less maintenanceRequires periodic spring replacement and lubrication
Power AdjustmentAdjustable via piston diameter, stroke, and gas pressureLimited adjustment options

Key Advantages of Gas Ram Technology

  • Tested to 200,000+ full-stroke cycles with less than 3% force degradation, ensuring consistent power output for decades of service life.
  • Force tolerance held to ±5 Newtons or ±5% (whichever is greater), guaranteeing precise velocity and energy consistency across every production unit.
  • Operational temperature range from ‑40°C to +80°C with no more than 2% force variation, delivering stable shooting performance in any climate.
  • Nitrogen gas leakage rate kept below 1% per year, preserving initial pressure and reducing the need for recharging or replacement.
  • Piston rods are nitrided to HV 700‑900 surface hardness, providing exceptional wear resistance and scratch protection for long-term smooth operation.
  • Stroke length accuracy within ±0.5 mm, ensuring precise fit and consistent piston compression for repeatable muzzle velocities.
  • Each gas ram is individually pressure‑tested and force‑calibrated at 20°C ± 1°C to guarantee that every unit matches your specified output.

​Air Rifle Gas Ram Applications

Tool Box Strut Applications

1. Break Barrel Air Rifles

Gas rams are widely used as the power plant in break barrel air rifles, providing a compact and reliable alternative to traditional coil springs.

2. Hunting Air Rifles

Used in hunting-oriented air rifles where consistent power, durability, and reliable operation are important for repeated outdoor use.

3. Target & Competition Air Rifles

Applied to air rifles designed for target shooting, where a smooth and consistent firing cycle is important for shooting performance.

4. High-Power Air Rifles

Gas rams can be engineered for higher-power air rifle platforms, with customized pressure and stroke specifications to match the required power system.

5. Recreational Air Rifles

Suitable for recreational and plinking air rifles, offering a durable gas-powered alternative to conventional spring systems.

6. OEM Air Rifle Manufacturing

Designed for air rifle manufacturers requiring customized gas ram dimensions, stroke lengths, pressure ratings, and mounting configurations for new or existing models.

Custom Solutions for All Major Air Rifle Brands

Gas ram technology was pioneered by Theoben in 1982, and has since become a proven powerplant adopted by leading manufacturers worldwide. Today, most major air rifle brands feature at least one gas-ram model in their line-up. GASTAC provides custom-engineered gas ram solutions that are fully compatible with virtually all of them – whether you are manufacturing new rifles or sourcing replacement power units.

  • Weihrauch – including the HW90K, which remains the company’s only gas-ram model and is based on Theoben’s original design
  • Theoben – the original pioneer of gas-ram technology
  • BSA – including GRT (Gas Ram Technology) models such as the Lightning XL SE and Supersport SE GRT
  • Gamo – including all IGT (Inert Gas Technology) models
  • Hatsan – including all Vortex Gas Piston models
  • Benjamin / Crosman – including Nitro Piston and NP2 models
  • Norica – including GRS (Gas Ram System) models
  • Webley – including D-RAM models
  • Umarex – including UX Syrix and ReAxis piston models
  • Stoeger – including Gas-Ram system models
  • Diana – including N-TEC gas piston models
  • Beeman, Browning, Beretta, Cometa, Remington, and many more

Different manufacturers use different gas ram systems – from Theoben-style designs to Crosman’s NP cylinders, Umarex’s “backwards” mounted ReAxis pistons, Hatsan’s Vortex system, and Gamo’s IGT units. Each has unique dimensions, mounting configurations, and force requirements. GASTAC does not offer a “one-size-fits-all” product. Instead, we custom-engineer each gas ram to match the exact specifications of your target rifle model

Tool Box Strut Applications

Frequently Asked Questions

Yes, gas rams are much more tolerant of being left cocked compared to traditional coil springs. Unlike steel springs that weaken and lose power when left compressed, a gas ram’s sealed nitrogen system does not suffer from the same fatigue. However, while it is often cited as a benefit, it is still not recommended as a habit—prolonged cocking places stress on other components such as the sear and linkage.

Gas ram air rifles are essentially maintenance-free by design. The sealed nitrogen unit eliminates the need for spring replacements and routine lubrication of the powerplant. However, you may occasionally need to treat the piston seal with a small amount of silicone chamber oil. Always use pure silicone oil—never use petroleum-based lubricants, as they can damage seals and cause dieseling.

Under normal use, a gas ram typically lasts 20,000 to 30,000 shots or more before requiring service. Some users report gas rams lasting for many years without issue. However, like any sealed component, seals can eventually degrade, leading to pressure loss. GASTAC gas rams are tested to 200,000+ full-stroke cycles with less than 3% force degradation.

The most common cause of pressure loss is seal degradation—the O-rings in the gland where the piston rod exits the cylinder can dry out and no longer seal properly. In some cases, a gas ram may fail suddenly rather than gradually losing pressure over time. GASTAC gas rams maintain a nitrogen leakage rate of less than 1% per year, preserving initial pressure for decades.

It depends on the type. Factory-sealed nitrogen gas springs cannot be rebuilt or repaired without very special skills and equipment. Some systems, such as the Theoben-style gas rams used in the Weihrauch HW90, can be user-recharged with a special pressure gauge and pump. Other types, like Hatsan’s Vortex air springs, can be rebuilt by replacing the O-rings and recharging with air. GASTAC recommends consulting your rifle manufacturer or contacting our technical team for specific advice.

Generally, yes. Gas rams produce less mechanical noise and vibration compared to coiled springs, resulting in a more civilized shooting experience. The firing cycle is smoother with minimal “twang” and reduced vibration. Some users describe the sound as a “quality soft phut” rather than the metallic twang of a springer.

Why Choose GASTAC

With unmatched quality, competitive pricing, complete pre- and after-sales support, and fast, secure delivery, GASTAC has become one of the world’s leading manufacturers of gas spring–based solutions.

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