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Smart Parts


Product Testing performed with DraXxus Paintballs

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Firebolt and 360 QEV
by Bill Mills - Photos by Dawn Mills - Dec 2006

Two of Smart Parts' upgrade parts for the Ion and SP-8 are the Firebolt and 360 QEV – and they are designed to work together.

QEVs made their first appearance in paintball on the Air Power Vector, and its progeny the Brass Eagle Rainmaker. A few years passed before airsmiths looking for an extra bit of speed started installing them on Autocockers.

A QEV, or Quick Exhaust Valve is a relatively simple pressure-operated pneumatics valve. In most electropneumatic paintgun designs, low pressure gas which controls a paintgun component such as the bolt in a spool-valve design or the recocking ram in an Autococker, is controlled by a low pressure solenoid valve. Gas flows through the valve to the ram or bolt, and pushes it in one direction. When electric current actuates the valve it allows gas to flow back out and be released to the air.

This means for a ram or spool valve bolt to move, it has to push gas back out through a hose and through the solenoid valve into the air every time it actuates. A quick exhaust valve mounts directly on the pneumatic ram, or close to the air port on a spool valve, often simply replacing a normal hose barb or elbow.

When gas is fed into the QEV, through its input side, pressure holds its internal valve shut. When the marker's solenoid valve (or even the mechanical 4-way in the case of a 'cocker or Vector) allows the gas line to vent to the outside, the gas pressure coming from the ram or solenoid valve has no opposing resistance, so it flips the QEV's valve open. Instead of having to push gas back down through pneumatics hoses and the solenoid calve, the ram or bolt only has to push it out of the QEV.

With a shorter path and less restrictions on the exhaust gas the ram or bolt faces less resistance – and that means faster cycling times.

It wasn't too long after Smart Parts released the Ion that aftermarket suppliers began shipping QEVs in an appropriate size for use with it, touting higher rates of fire possible with faster bolt movement.

paintballThe Ion uses banjo bolts – elbows with gas-through screws in their centers – as the air fittings connecting to the Ion's inner receiver. These banjo bolt elbows can be screwed into place, without having to twist the entire elbow. The aftermarket QEV's on the other hand, were elbow shaped, and the entire QEV needed to be turned when they were screwed into place.

This led to a problem, in that the Ion's polymer body cover got in the way, it didn't leave room to twist an aftermarket QEV. QEV users were left with the options of switching to an aftermarket body, or cutting “turning room” into the bottom of the stock body (not a difficult task.)

paintballSmart Parts response was the 360 QEV – so named because it can pivot 360 degrees. Like the stock elbows the 360 QEV uses a gas-through banjo bolt design, meaning it can be installed easily without interfering with the stock Ion body cover.

The 360 QEV installs in the Ion by degassing the marker, separating the body from the grip frame (removal of the two grip frame screws and the body flat cap screw) and unscrewing the middle of the three banjo bolts from the body breech.

paintballThe standard Ion banjo bolts use a releasable compression fitting to attach to the internal pneumatics hoses. The 360 QEV on the other hand uses an internal barb fitting. The difference in the type of fitting and the size of the part required about 1mm of hose to be trimmed off for a proper fit when testing for review. A super thin layer of SL33K (Smart Parts house brand of lubricating grease) on the outside of the hose barb allowed it to slide easily into the hose.

To find out what difference the QEV made to the bolt closing speed, the test Ion was adjusted to the minimum dwell value that would reliably close the bolt, and these values recorded both with the 360 QEV and the standard banjo bolt fitting.

In stock configuration the Ion required 21 milliseconds of dwell to close the bolt completely. With the QEV in place, this dropped to 16 milliseconds – a difference of five milliseconds.

paintballThe second part of this upgrade equation came in the form of the Firebolt. With the bolt closing faster, it hit its front bumper o-ring harder, and Smart Parts designers noticed an increase in wear on this part. Since inertial energy consists of velocity times mass, reducing either one will reduce inertia and impact. With no point in slowing the bolt down, the Firebolt was built as a lighter version of the stock bolt.

paintballWhile its external shape is nearly the same as that of the stock bolt, the Firebolt is hollow in its front and center sections. The result is a bolt that weighs only 0.5 ounces, compared to the 1.1 ounce stock bolt. At any given bolt speed that's less than half the impact energy on the bolt's bumper o-ring.


The Firebolt and QEV combination dropped the dwell time needed to close the bolt down to 16ms, a reduction of 6ms from the completely stock configuration. While longer dwell times are needed to consistently fire a paintball at field velocity, these times will be decreased specifically by the amount of time needed for bolt closure.

paintballWhile not so easily measured, the combination of the Firebolt and QEV gave a reduction in perceived recoil or shake with each shot. This was an expected result as the total mass moving back and forth inside the paintgun with each shot was reduced by more than half with the installation of the Firebolt. Also noted in field use, was that a slight drop in operating pressure was needed to offset the increase in fire chamber volume created by the hollow center section of the Firebolt.

Because the Ion and SP-8 use the same internal receiver structure the Firebolt and 360 QEV can be used with either. The Firebolt ships as the stock bolt for the new Epiphany. The 360 QEV however is not compatible with the Epiphany as it is not rated for use in the correct pressure range.

The Firebolt and 360 QEV are simple to install upgrade components for the Ion or SP-8. Specifically the banjo bolt design of the 360 QEV meant it could be dropped in without having to modify the Ion body. Combined, these two offered a measurable decrease in the amount of time required for the bolt to close, and thus an overall reduction in cycling time.

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