US Army Alpha Black Tactical
by Bill Mills - Photos by Dawn Mills - June 2009

Few of today's players have been around long enough to remember paintball, “back in the day” but the phrase “everything old is new again,” certainly has meaning, as ideas from paintball's past are reapplied to new products in its present.

In the mid 1980s, it was not unheard of for airsmiths to “swiss cheese” the hammers on customized pump action markers. By drilling holes into a marker's hammer, its weight would be reduced, creating less kick, or recoil as the marker was fired.

Typically this customization was also accompanied by polishing the hammer, to give it a smoother, lower friction finish, making both the pumping and firing cycles smoother. Typically it was also accompanied by changing spring tensions, to compensate for the hammer's reduced inertia.

These are the same principles applied in TechT Paintball Products' Zero Kick Bolt for Tippmann and BT markers, though instead of requiring custom work and a machine shop, the Zero Kick is ready to go drop-in upgrade.

Because Tippmann's Model 98 line, A5 and X7, as well as BT's markers share a common hammer structure, the Zero Kick bolt is designed to work with all of them. In general shape it is very close to the stock hammers, with the notable exception that the ramp on the lower back of the bolt is not a simple flat surface as with the stock hammer. Instead is is a multi-angled cut, to provide less resistance as it pushes the marker's sear while the hammer is resetting to the cocked position.

The center of the bolt is hollow, and eight lightening holes are drilled in its sides and top, reducing the total amount of mass. A machined, lightweight resin insert fits inside the hammer, to guide the marker's spring and prevent it from kinking. In addition to its center opening for the spring, the insert is drilled left to right, for a Model 98's cocking handle.

The Zero Kick Hammer weighed in at 2.4 ounces, less than half the mass of the stock A5 hammer's 5.3 ounce weight. The hardened metal of the Zero Kick hammer was also coated with electroless nickel plating, resulting in a hard, bright finish.

For review the Zero Kick hammer was test fit in both a Model 98 Custom and an A5. Installation was first done on the A5, where it is a rather simple process - pulling body pins, the rear cap, ASA and pivoting the grip frame down allows the entire valve assembly to be removed from the rear of the marker.

Upon re-assembly with the Zero Kick hammer, the valve assembly did not slide easily back into the A5 body. The link rod, which connects the hammer to the marker's bolt was not able to sink quite far enough into the hammer. Instead the link was stopping against the hammer's insert so that its top edge bound up against the receiver when trying to slide the valve assembly into place. Either the link rod was a little too long to work with the aftermarket bolt, or the aftermarket bolt a little too long for the link rod. While this was a situation that would normally be resolved by Tech T's included lifetime warranty, a much faster solution was used to allow immediate installation and testing – simply drilling a hole a small hole in the insert, allowing the link rod to seat itself further into the hammer.

Installation in a 98 Custom was trouble free, though more involved, as that marker design requires disassembly of the receiver halves, and proper alignment of internal assembly pins and springs during reassembly.

When firing the A5, the difference in kick between the stock hammer and the Zero Kick hammer was significant enough to easily notice. Although some recoil still existed, the marker's feeling, even when rapid firing, was noticeably smoother.

Changing hammer weights is not something to be done with impunity. A hammer must have enough mass to knock open the marker's valve long enough and far enough to deliver enough gas to fire a shot. Tippmann's choice in hammer weight was designed to provide reliablie operation under a wide range of conditions. A lighter hammer will accellerate faster, delivering a similar level of impact energy, but it may not have the inertia to hold the valve open as long, affecting velocity.

Firing the A5 with the Zero Kick bolt, the marker's velocityy adjuster had to be opened up to maintain the 280 feet per second that gave a good spin from its Flatline barrel, while using CO2 as a power source. The Zero Kick Hammer was performing as it should. In cooler weather, or with HPA players using reduced weight hammers should be prepared for the possibility of changing mainsprings, or adjusting mainspring hammer tension with a rear velocity adjuster to compensate for the reduced mass.

With a universal design to fit a range of Tippmann based markers, the Zero Kick Bolt created a noticable reduction in kick while maintaining a higher-end finish than the stock component it replaced.