K-CQB
by Bill Mills - Photos by Dawn Mills - Aug 2007

How It Works

Features HowItWorks Disassembly Testing Data

Functionally the K-Series relies on long standing blowback operational valve format. Its implementation is in a modular body which provides significant flexibility in configuration, much of which is focused on providing a look and feel similar to military/police firearms, while utilizing a unique new loading system to achieve this goal.

The hammer, link rod, bolt and general valve power tube shape will look very familiar to those who have worked with the Tippmann, A-5, as they operate similarly. What's inside the valve body is a bit different however. The K-Series markers utilize a removable valve body inside the power tube valve assembly and poppet valve core that are very similar to those used in most stacked tube blowback markers, and in some cases may be interchangeable.

At rest, the hammer in the marker is held back by the sear, a latch extending up from the trigger assembly. Behind it, the mainspring is compressed against the backplug (in this case the mount plug of the stock.)

When the trigger is pulled, it tilts the sear, releasing the hammer. Pressure from the mainspring drives the hammer forward. The link rod connects the bolt and hammer, so the bolt moves forward as well, pushing a paintball into the rear of the barrel, and sealing against it by the time the hammer is far enough forward to strike the valve.

The valve core is pressed against the valve face by the valve spring as well as the gas pressure behind it. This design helps compensate a bit for changes in gas pressure, especially those encountered with CO2. As the gas pressure rises, the valve becomes harder to open and closes more quickly, as the pressure lowers it becomes easier to open and closes more slowly.

As the hammer gets further forward, it slides into the back of the power tube, and the hammer o-ring makes a loose seal against it. The hammer continues forward and strikes the pin of the valve core, pushing it forward.

This lifts the cup seal, the soft part of the valve core away from the valve face, allowing gas to flow from the valve chamber into the valve, then up through a hole in the top of the valve and into an internal gas passage in the power tube.

The gas flows from here into a chamber in front of the valve, and out the front end of the power tube, through the hollow core of the bolt, and into the back of the barrel where it pushes a paintball out, as it expands until its pressure equalizes with the surrounding air.

Velocity is controlled by a brass sleeve inside the front of the power tube. It can be adjusted to move closer to or further from a screw, which serves to baffle the gas flowing through it, delaying it enough to affect velocity.

HGP includes a velocity adjustment tool (not to mention a screwdriver, wrench, hex wrenches and cartooned soldier sticker) with the K-Series markers. The tool is long enough to insert down the barrel, through the bolt, where it can engage slots in the front of the velocity control tube. Turning the tube clockwise pushes it back further and decreases velocity.

The K-Series manual also suggests making adjustments to the screw the tube backs against, though it was found during testing, that velocity reduction was much more effectively achieved with the adjuster tool and velocity control sleeve.

The rear of the valve core's pin has been ground flat on one side. When the hammer has depressed the valve core, this flat spot creates a gas passage, and a portion of the gas let into the valve jets backward to the up against the hammer face.

Because the hammer face is sealed against the outer wall of the power tube, it forms a piston, and the gas released into it drives the hammer backwards compressing the mainspring and taking the link rod and bolt with it. When the hammer blows past the sear, the sear resets, and holds the hammer back, waiting for the next shot.

Continue to Disassembly .