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China based Paintball Assassin has included the Deathstix carbon fiber barrels in their product line-up of packs and other accessories.
The term “carbon fiber” is thrown around often in paintball, with players often referring to products as “carbon fiber” when they are really plastic or other materials with a carbon fiber weave pattern printed on them.
True carbon fiber construction is very similar to woven fiber glass, with the individual fabric strands being made carbon, rather than glass. Carbon fiber fabric is stronger than fiber glass, yet lighter in weight. Like it's glass cousin, carbon fiber is flexible and not extremely resistant to crushing forces. Both fibers are used to form parts by soaking and coating them in resins such as polyester or epoxy to create a composite material.
The resin provides stiffness and structure, while the fabric provides shear and tensile strength. When the resin is left clear (no dyes added to make it opaque) the fibers of the structure are visible, with the distinctive and well known carbon fiber weave look. In some applications where fiberglass performance will meet the task, it is not uncommon for fabricators to build a part of primarily fiberglass with opaque resin, and a top layer of carbon fiber with clear resin to produce a “carbon fiber” part at a reduced expense. Tube shapes, like paintgun barrels are formed by wrapping resin soaked cloth around a cylindrical mold, known as a mandrel.
Although carbon fiber composites provide better strength to weight and volume ratios than fiberglass, and many other materials, they also have their limitations. They typically can not be shaped effectively by machining, and the relatively brittle nature of the resin means they are not adequate for fine threaded connections, such as the interface between a paintball barrel and marker.
The Paintball Assassin Deathstix barrel system is a two-part design. Aluminum breech sizers are connected to a ported carbon fiber barrel, available in 14 and 16 inch lengths.
The Deathstix sample reviewed came in a case that made a much greater impression than the clear plastic packing tubes used by many barrel manufacturers over the years. With Deathstix graphics inside and out, and a padded interior, the faux-leather bound box features a spring loaded lid that pops to the open or closed position. While suitable for protecting the barrel from chipping or other damage in a gear bag, it is definitely designed to make an impression in a retail store display.
The sample barrel reviewed was a 14-inch model, with the Paintball Assassin's red carbon gloss finish. The Deathstix barrels are available in a variety of finishes – some, such as the gloss which show the pattern of the carbon fiber cloth, and some with designs such as camo patterns covering the entire barrel front.
The barrel front is 12-1/8 inches long, comprising of a carbon fiber composite tube that is 0.075 inches thick over most of its length. At the rear of the barrel section is an aluminum threaded fitting. The fitting is sleeved over the back of the tube, which has a reduced outer diameter. This allows for more practical aluminum attachment threads, but maintains the carbon fiber composite surface over the entire bore interior.
The red gloss finish is a red tinted clear resin over the woven carbon fiber material, with a glossy finish. At a few points, surface imperfections could be found where dust particles had come in contact with the resin before it had cured, but these were very small and only noticeable on close inspection.
The last 6-1/2 inches of the barrel are ported with five rows of 0.055-inch diameter holes. The holes are arranged in five rows, spaced 0.043 inches apart, up to the last 2.9 inches of the barrel, where the orientation of the rows shifts 36 degrees and the spacing closes up to 0.25 inches between holes.
The inner diameter of the barrel measured with calipers to 0.699 inches at the muzzle, and 0.698 inches at the rear.
Graphics imprinted on the barrel bear the Deathstix logo, “carbon fiber technology” and the word “kill” with arrows pointing to the muzzle.
The four back pieces included with the barrel can be attached to it one at a time, via left hand threads. The two pieces must be screwed together counter-clockwise instead of clockwise. An o-ring on the barrel provides friction to keep the sizer screwed on snug.
Each sizer back is engraved with the marker thread standard to which it was built – in the case of those used in this review, that was A/C for Autococker. Each sizer was also laser engraved with a bore diameter - .686, .689, .692 and .695. Approximately the first quarter inch of each sizer is tapered, to allow smooth paint entry to the control bore. The total length of bore surface, including the tapered entry zone is 1.357 inches.
Caliper measurement of the control bore sections of each of the backs yielded values of 0.684, 0.687, 0.690 and 0.694 inches.
The front barrel section weighed in at 2.5 ounces, with the control bore backs at 0.7 ounces each, giving the assembled barrel a weighing in at 3.2 ounces. A weigh in of other brand 14-inch aluminum barrels gave weights of 5.0, 4.4, and 4.7 ounces – an average of 4.7 ounces. The Deathstix barrel was 68 percent of that averaged aluminum barrel weight, showing the light-weight advantage of fiber composite construction.
For testing, the Deathstix barrel was mounted on a Matrix LCD equipped with a Crossfire compressed air system and Prophecy loader, bench mounted and fired at paper targets under microprocessor control for 20 shot groupings at a precise rate of 1bps. Distance to target was 75 feet with DXS Gold paintballs using each of the barrel's four breech sizers. Velocity settings on the marker were not changed from group to group, so that an increase or decrease in average velocity could be seen as a sign of gas efficiency differences between the sizers.
Consistent with previous testing of other barrel kits, the velocities from the shot groupings with the tighter backs were more consistent than those with the larger bore backs. Despite the relatively short length of the control bore backs they produced a very measurable impact on velocity performance. The tighter sizes also delivered higher average velocities from gas bursts of the same pressure and duration, indicating better gas efficiency with a tighter fit.
Also consistent with past testing of other systems, the grouping with the best accuracy was not the grouping with the best velocity consistency. The .692, or third sized back (green in the overlay image) produced the tightest grouping, though the variance in grouping size was not very great between the different backs. Paintball players will typically select a barrel bore size by “blow through” testing – placing a paintball in the back of a barrel, and blowing it out like a blow gun – selecting a barrel or sizer which will hold the paintball and keep it from rolling out, but allow it to blow out easily. This testing, though subjective, indicated the .692 as the insert of choice, and was on the mark for selecting the back which provided the best accuracy. For target and chrono data, CLICK HERE.
The Deathstix barrel is a well presented product, with eye catching looks, and a measurable weight saving over its all aluminum counterparts. Its bore sizing back sections, while short in length produced a measurable effect on both consistency and accuracy performance under controlled testing.
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