Fine-tune your HPA system’s performance with the PolarStar Kythera M3 Orifice Screw (Size 0.19"), a precision-engineered metering screw designed to regulate the nozzle return speed in your Kythera SA system. Built to PolarStar’s exacting standards, this orifice screw gives advanced airsoft technicians and enthusiasts the ability to customize their rifle’s air efficiency, cycle timing, and rate of fire for optimal reliability and performance.

Precision Control for HPA Performance

At the heart of the PolarStar Kythera’s mechanical system is a metering screw that controls airflow into the dump chamber. The M3 orifice screw features a precision-machined internal orifice that determines how quickly the nozzle returns to its forward position. A smaller orifice slows down the nozzle speed, while a larger one allows faster cycling. The 0.19" size strikes a perfect balance — offering smooth, consistent feeding and controlled return motion without sacrificing rate of fire.

Whether you’re optimizing for smooth semi-auto precision or balancing high-speed automatic performance, this orifice screw helps you achieve the ideal timing for your unique setup.

Fine-Tuning Nozzle Speed and Rate of Fire

PolarStar designed the Kythera SA to be fully mechanical yet adjustable in key aspects of its operation. The M3 orifice screw directly influences how fast air refills the dump chamber, which in turn affects the nozzle’s forward movement. A smaller orifice size reduces flow, slowing the nozzle’s return and lowering rate of fire — ideal for high-pressure setups or situations where you want maximum control over each shot.

As of serial number 4581, Kythera SA units ship with a 0.024" screw installed as standard. The 0.19" orifice provides slightly slower nozzle speed, making it perfect for players who prefer a balanced firing response with reliable feeding.

Orifice Size and Pressure Relationship

One key factor to understand is how input pressure interacts with orifice size. Smaller orifices limit recharge rate and reduce nozzle speed at the same air pressure. However, in most cases, these smaller orifices are used at higher input pressures — where air velocity is naturally increased. This means that while the orifice reduces speed, it helps maintain a consistent firing rhythm and prevents over-cycling that could cause feeding issues or double feeds.

If your Kythera system is already cycling reliably, there’s typically little to gain from drastically reducing nozzle speed. The 0.015" screw, for instance, is designed for extreme flow reduction and is not recommended except in highly specific tuning scenarios.

Easy Installation — Handle with Care

Each PolarStar Kythera M3 Orifice Screw is designed with a 1.5mm hex drive for precise installation. However, due to its small size and delicate machining, it’s important to use care when handling. The manufacturer strongly advises that the screw be installed finger-tight only — no torque required — to prevent stripping the hex drive or damaging the screw’s threading.

Compatibility and Construction

This metering screw is fully compatible with the PolarStar Kythera SA system, providing a direct drop-in replacement for your existing screw. Manufactured from high-quality materials under PolarStar’s strict quality control, it ensures precision airflow metering, durability, and long-term stability in your HPA system.

Why Choose PolarStar

PolarStar Precision Airsoft has been setting the gold standard for HPA innovation since 2009. From their industry-changing Fusion Engine to the fully mechanical Kythera SA, PolarStar continues to lead the market with unmatched reliability and precision craftsmanship. Every component — including small parts like the M3 Orifice Screw — reflects their commitment to performance and engineering excellence.

When you choose PolarStar, you’re not just buying a part — you’re investing in a system designed by engineers, tested by professionals, and trusted by top airsoft players worldwide.

Key Features:

• Regulates nozzle return speed and flow rate

• Precision orifice machining ensures consistent airflow

• 0.19” orifice provides balanced performance for most setups

• Compatible with PolarStar Kythera SA HPA systems

• Allows for custom tuning of nozzle speed and rate of fire

• Durable metal construction for longevity and reliability

• Easy installation with 1.5mm hex drive (finger tight only)