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

Testing

Features HowItWorks Disassembly Testing Data

Testing of the K-CQB started with checking reliability of the spring fed magazine, as it is an innovative and relatively unique component. On the WARPIG Ballistic Labs test stand, a microprocessor controlled pneumatic actuator was used to fire the K-CQB receiver (less barrel, in order to capture paint at low velocity to inspect for breakage) at precise rates. The magazine was loaded with 16 paintballs. At both 6 balls per second and 10 balls per second, the K series magazine had no problems feeding the entire 16 rounds reliably. Six balls per second is a relatively high rate of fire for a typical player with a mechanically triggered blowback marker like the K-Series, and 10 is above what most will ever be able to reach.

Initial velocity adjustment proved a bit tricky, as initial velocities were well above 300 feed per second. In attempting to lower the velocity, the down-the-barrel velocity adjuster tool seemed to have more impact than attempts to adjust the side velocity screw. Use of the down-the-barrel tool required unloading the marker for each adjustment, in order to provide a clear path for the tool into the center of the bolt and the power tube. After a bit of trial and adjustment, the velocity on single test shots hovered in the low 280s (target was 285) and was not further adjusted.

Velocity stability testing was performed with the same test stand, the marker secured to a Custom Cylinders steel marker stand, powered by a Crossfire high-output compressed air system and utilizing the feedneck and magazine port blocker to feed DraXxus Hellfire paint to the marker via a Boost Hoppers modified VLocity Loader. The pneumatic trigger actuator and microprocessor controller were again used to fire the K-CQB, this time over a ballistic chronograph, recording strings of 30 shots at first 1 and then 12 shots per second.

While the velocity was less consistent when rapid firing than slow shooting, the average velocity for both strings was identical, meaning the K-CQB showed absolutely no signs of gas starvation or shoot-down.

The standard deviation rose markedly under rapid fire from 17 to 26, the spread between the high and low shots jumped from 27fps to 144fps. The 95% +/- figure is an easier way to comprehend how consistent (or inconsistent) the velocities were. It is calculated by discounting the worst 5% of the shots – figuring they are probably due to paint inconsistencies or other flukes. The 95% most consistent shots are then compared to see how close they are to the average. At 1 shot per second this figure was 7. At 12 shots per second it went up to 11. Complete chrono data is available here.

Target groupings were fired at a range of 75 feet, with 20 shots at a range of 1 ball per second under microprocessor control both with the stock All American barrel and a Freak barrel with All-American front and .687 insert matched to the paint – the barrel used as a control standard in WARPIG Ballistic Labs marker testing. The control barrel produced a tighter grouping than stock. Individual target photos are available here.

For Hummer Godforce Paintball and their US importers, the K-Series markers representa move to a design that is more of a blend between a complete firearm simulator and a milsim themed recreational paintball marker. Its maintenance and repair are more similar to existing recreational markers than their earlier T68 and .43 caliber models. It is also more readily compatible with a wide variety of existing aftermarket accessories, such as stocks for the Tippmann A-5. The K-CQB configuration has no shortage of accessory mounting options with its tactical rails. Its ability to adapt quickly between two different feed styles offers flexibility, and its reliable magazine feed system is a unique innovation valuable for police and military training, or simply to milsim players who want their style of play to more closely mimic real world tactical operations.