STALKER Scorpion Piston + Spring Guide Set for SRS

The Stalker Scorpion is an advanced modular piston system designed for the Silverback SRS platform. Its main advantage is the ability to adjust piston weight, overall piston length and Air Brake settings according to your individual rifle configuration.

When properly tuned, the system can provide quieter operation, improved energy consistency and optimized piston movement. It also works with the Open Piston Sear.

Modular piston weight

The piston body is made from interchangeable weight sections. The kit includes:

• 5× aluminium weights – 3 g each
• 4× stainless steel weights – 11 g each
• aluminium piston head – 7 g
• stainless steel piston head – 17 g

By combining these components, the piston weight can be tuned to influence piston speed, sound and overall rifle behavior.

The supplied information lists an approximate adjustable range of 65–148 g, while the detailed configuration chart lists setups from approximately 62–145 g. The listed 145 g configuration additionally requires a fifth stainless steel mid-section weight, sold separately.

Adjustable Air Brake

The kit includes two adjustable 3.80 mm Air Brakes:

• Short Air Brake – recommended mainly for approximately 2–3 J and higher setups
• Long Air Brake – recommended mainly for approximately 2 J and lower setups

The Air Brake controls piston behavior at the very end of its travel. Correct adjustment helps reduce piston impact noise against the cylinder head while fine-tuning the use of air inside the cylinder.

Manufacturer's general rule:

Higher Joule = shorter Air Brake
Lower Joule = longer Air Brake

The selected Air Brake can be secured with the included locking nut.

Short Stroke option

The modular weights can also be used to extend the piston body, creating a Short Stroke configuration.

This reduces the bolt pull distance for quicker and shorter reloads. However, extending the piston also reduces usable cylinder volume and can lower energy output. Depending on the setup, this can be compensated for with a stronger spring.

High Joule Piston Cup

A High Joule Piston Cup is included for higher-energy configurations and, according to the manufacturer, also helps provide a lighter bolt pull.

For optimum results, the manufacturer recommends applying a small amount of suitable oil or silicone oil to the edge of the piston cup.

Manufacturer performance example

The manufacturer provides the following reference setup:

• Rapax Lightpull Blue 2J+ spring
• Stalker SRS Cylinder
• 420 mm inner barrel
• approximately 2.2–2.3 J

The standard SRS cylinder may produce lower energy. Actual results can vary depending on the cylinder, barrel, bucking, BB weight, spring, piston weight and other components.

Air Brake tuning guidelines

The manufacturer recommends:

• correctly setting the Hop-Up for your chosen BB weight
• selecting the appropriate Air Brake for the energy level
• adjusting its length gradually
• finding the quietest position without losing energy
• if energy begins to drop, screw the Air Brake back in slightly

Package Contents

• 1× Stalker stainless steel Scorpion spring guide
• 1× shock-absorbing rubber insert for the spring guide
• 1× High Joule Piston Cup
• 1× aluminium piston head
• 1× stainless steel piston head
• 5× aluminium weights
• 4× stainless steel weights
• 1× stainless steel Sear End Cap – 15 g
• 2× adjustable Air Brakes – Long + Short
• 1× Air Brake locking nut
• 10× O-rings for the weights / cylinder head
• 2× spring guide O-rings for the SRS A2 butt plate
• POM front and rear guide rings

Key Features

• Compatibility: Silverback SRS
• Works with: Open Piston Sear
• Manufacturer recommends pairing with: Stalker SRS Cylinder
• Modular design: yes
• Adjustable piston weight: yes
• Adjustable Air Brake: yes, 2 versions
• Short Stroke option: yes
• Weight materials: aluminium / stainless steel
• Guide rings: POM