Stryker STR-1
by Bill Mills - Photos by Dawn Mills - May 2008

Features HowItWorks Disassembly Adjustment Testing Data

HOW IT WORKS

The Stryker STR-1 is a blowback powered semi-automatic marker. Its stacked tube design was pioneered with the FAST Illustrator and Line SI Promaster, and has been the operating design for literally hundreds of paintgun designs.

The Striker is laid out in essentially two tubes inside of its body. In the lower tube is a popped style exhaust valve. The gas chamber in front of that valve is fed by CO2 or compressed air from the gas-thru grip.

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At rest, the Stryker's mainspring is compressed between the hammer and back plug in the lower tube. The sear, a see-saw like latch sticking up from the grip frame holds the hammer back.

In the upper tube like the bolt, linked to the hammer with the link pin. In front of the bolt is the breech and paintball.

When the trigger is pulled, it tips the sear, releasing the hammer. The mainspring expands, pushing the hammer forward until it strikes the valve. Because they are linked, the bolt slides forward with the hammer, pushing the paintball into the back of the barrel and blocking off the feed port.

When the hammer strikes the valve it pushes in on the valve core. This pushes the core's cup seal away from the valve body, and allows gas into the valve. The rapidly expanding gas has two places to go. A small amount rushes past the valve core's pin up against the face of the hammer, while the bulk of the gas travels up through an opening in the valve and into an opening in the bolt.

The gas then expands through the hollow center of the bolt, and pushes the paintball out of the barrel.

Meanwhile, the smaller amount of gas released out the back of the valve pushes back on the hammer. This causes the hammer to reset to its rear position, retracting the bolt and re-compressing the mainspring before the hammer catches on the sear to wait for the next shot.

A velocity adjuster screw in the back plug changes the amount of pressure on the mainspring. When the screw is screwed inward, it increases pressure in the mainspring, so the hammer hits the valve with more force, opening it further and longer to allow through more gas, resulting in more energy, and thus more velocity delivered to the paintball.

The mechanically triggered valve system offers semi-automatic (one shot per trigger pull) operation only, although an electronically triggered variant of the Stryker is available. Using the control of a microprocessor to allow multiple firing modes, the electronic trigger system uses an electrical solenoid, rather than the mechanical force of the trigger to trip the sear and release the hammer, while the valve system operates the same.

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