Jan. 2011 • TACTICAL WEAPONS 15

The .408 Cheyenne Tactical (.408 Chey Tac) cartridge is a military and LE long-range precision tactical cartridge

whose time may well have come. The origi-nal round was developed by Dr. John Taylor and William Wordman in the United States in 2001 to provide a precision tactical cartridge with precision accuracy out to 2,000 meters. The .408 Chey Tac essentially uses a modi-fied and necked down .505 Gibbs case and launches either a 305-grain bullet at 3,500 FPS (feet per second) or a 419-grain bullet at 3,000 FPS with a muzzle energy of more than 8,000 ft-lbs (foot pounds). By compar-ison, a 168 grain .308 match cartridge has a muzzle velocity of only approximately 2,600 fps and 2,180 ft-lbs energy. The .308 is totally overshadowed by the .408 Chey Tac, although our Thor XM408 test rifle was only marginally heavier than precision tactical rifles chambered for the .308.

The modular tactical rifle ready for military and LE hard-target, 1,500-plus yard duty!

By Charlie Cutshaw

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14 TACTICAL WEAPONS • Jan. 2011

The Thor XM408, chambered in the extremely powerful .408 Chey Tac cartridge, offers shooters a long-range precision rifle with 2,000-meter capability in a package that weighs less than comparable .50 BMG rifles. It also breaks down easily for transportation.

Main Photo Sean U

tley

Doug Richardson Photo

Jan. 2011 • TACTICAL WEAPONS 17

Anti Materiel RoleThe .408 Chey Tac is

intended not only for antipersonnel purposes, but for antisniper and antimateriel use, as well. Naturally, a large cartridge like the .408 Chey Tac will deliver more felt recoil than lesser cartridges, but this can be offset by the use of muzzle brakes. The Thor XM408 brake reduces felt recoil to approximately that of a .308, although muzzle blast alongside the rifle is pronounced and distracting. The spotter on a precision tactical team using an XM408 should position himself slightly to the rear of the shooter’s shoulder to avoid having gases blown into his face.

Built For DutyFor military and law enforcement use,

where does the .408 fit? For the military, the .408 gives the precision tactical marksman a range advantage over any .308 or .338 caliber rifle, while adding little more to the weight burden that every Infantryman must contend with. Our test XM408 for example, tips the scales at 26 pounds. When com-pared to .50 BMG caliber rifles, our XM408 weighs less than the lightest weight .50 BMG rifle we have ever tested. The XM408 that is the subject of this evaluation can be used at distances of more than 1,500 yards with superb accuracy. At closer ranges, especially those associated with MOUT (mil-itary operations in urban terrain) that char-

acterize much of the operations in Iraq and for law enforcement, where engagement distances are almost never farther than 100 yards/meters, the .408 offers the precision marksman the capability to defeat targets that would resist any .308 bullet and many .338 Lapua Magnum rounds.

For law enforcement, the .408 bears examination as an alternative to .50-cali-ber rifles simply because most organiza-tions do not require the terminal ballistics of the .50 BMG cartridge, but wish to have a rifle available whose ballistics exceed those of the traditional .308 for positive vehicle stops, defeating hard targets such as brick walls and other situations where the .308 or .223 isn’t sufficient, but where use of a .50 BMG rifle might be “overkill” and negatively viewed by civilians or the news media. Also, the .408 is one of the few cartridges whose bullet will reliably penetrate aircraft wind-shields and retain sufficient terminal ballis-tics to eliminate targets in aircraft cockpits.

The Thor XM408 is derived from the EDM Arms Windrunner and in fact is manufac-tured under license from EDM. The XM408 is a bolt-action rifle fed from a detachable box magazine, but differs in its construction from any conventional bolt-action rifle. The

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16 TACTICAL WEAPONS • Jan. 2011

The Thor XM408 employs a robust action made from steel and feeds from a detachable box magazine. Note the spiral grooves on the body of the rifle’s bolt.

The XM408’s stock is fully adjustable for

both length of pull and cheekrest height, mak-

ing it infinitely adapt-able to a wide range of

tactical operators.

Doug Richardson Photos

Jan. 2011 • TACTICAL WEAPONS 1918 TACTICAL WEAPONS • Jan. 2011

XM408 is manufactured almost entirely of steel and aluminum alloy. The steel receiver and bolt are CNC and EDM machined and hardened to 42 Rockwell.

Mission AdaptableThe XM408’s stock assembly is fully

adjustable for length of pull and cheek-rest height. The XM408’s only non-metallic components are the pistol grip, borrowed from AR-15 type rifles, and the buttstock pad. The XM408 comes complete with an M60-machine-gun style bipod and a fold-ing adjustable monopod in the buttstock assembly. Like the EDM Windrunner, from which it is derived, the XM408 can be bro-ken down into a compact package for transportation or airborne operations in less than a minute. The stock is fully col-lapsible and the barrel is removed by sim-ply twisting off the large retaining nut that automatically sets proper headspace when tightened into place. No tools are necessary to disassemble or reassemble the XM408. The barrel slides into place and is automati-cally indexed via a notch in the receiver. There is no torque requirement for the bar-rel nut; all that is required is to firmly hand-tighten it into place. The fluted XM408 bar-

rel is, of course, free floated along its entire length as a part of the overall design.

The XM408 is a conventional bolt action rifle in the sense that it has a manually oper-ated bolt with two forward locking lugs and a safety lug that is integrated into the oper-ating handle, but the design is otherwise unconventional. The XM408 has a “float-ing” bolt head that flexes slightly to ensure proper lockup and headspace. The extrac-tor is integral to the right locking lug and the ejector is of the plunger type, positively ejecting spent casings. During testing, our XM408 placed every spent casing in a small pile about 6 inches from the right front of the ejection port. Unlike most bolt-action rifles, the XM408 receiver body surrounds the bolt, adding strength and rigidity and also protecting the rifle’s action from dust and foreign matter.

The receiver’s top surface is fitted with a MIL-STD-1913 rail for mounting optics. There are no open sights. The safety is a small lever at the right rear of the receiver that is applied when moved to the rear and released when pressed forward, like that of a Remington 700. The safety physi-cally blocks the trigger, although the bolt can still be manipulated. The “single stack”

EXTREME RANGE TESTFIRE»detachable box magazine holds five cartridges. The magazine is retained at the rear by a latch that engages a notched plate spot-welded to the rear face of the magazine. The attachment is positive, although there is some intentional play at the forward end of the magazine. Feeding was absolutely reliable and was butter smooth.

Our XM408’s bolt operation was initially somewhat “gritty,” but after wip-ing it clean and applying a light coat of Mil-Comm’s TW-25B PTFE spray to the bolt and the receiver interior, the action smoothed considerably. The owner’s man-ual states that the action might seem rough at first due to the phosphate finish and that it would become smoother after some usage and lubrication, but TW-25B instantly smoothed the bolt’s operation. For high-shear applications such as locking lugs, a tiny amount of TW-25B PTFE grease enhances operation and reliability.

Leading-Edge OpticsWe set our XM408 up with a Leupold

Mark 4 6.5-20x 50mm scope with optional Horus Vision H25 tactical reticle which was recently adopted by the U.S. Marine Corps as its standard scope sight.

In use, the shooter generates “come-up” data using the handheld Trimble TDS Recon computer with Horus Vision ballistic soft-ware installed. This data is transferred to a waterproof, adhesive-backed paper card that is used to determine precise holdovers for elevation and windage. If time is avail-able and exact precision is desired, the TDS Computer can be used to generate specific targeting data, to include elevation and

windage holds for the target to be engaged. Once the rifle is zeroed with one load, the hand-held computer can be used to generate come-up

cards for other loads. The ballistic data for other loads is entered into the TDS and a separate “come-up” card generated. All that is necessary is to generate a come-up card for any load desired and confirm zero.

Another recent Leupold product is the company’s RX series of digital laser rangefinders (LRF) that deliver the exact ballistic distance to the target, regardless of slope. Most rifle shooters know that as the angle up or down increases, the true bal-listic distance decreases. Previous devices measured the cosine and read out a factor by which the shooter multiplied to obtain the true ballistic distance. This took pre-cious time, during which the target might go behind cover and disappear. Of course, there were “whiz wheels” and slide rules to speed obtaining the true distance, but

Caliber/aCtion: .408 CheyTac/bolt

length: Extended 54.5", 138.4cm Collapsed 48", 121.9cm

Weight: 26 lbs, 11.79kg

barrel: 30", 76.2cm

tWist rate: 1:13 twist

Magazine: 5 round standard 7 round optional

rail length: 10", 25.4cm

aMMo high loW average extreMe std. average veloCity veloCity veloCity spread deviation group

Chey Tac 2845 fps 2795 fps 2820 fps 50 fps 15 0.65 in419-gr.FMJBT

Performance

Testing conducted at 100 yards. Velocity data taken from 5 shots, Chronographed on Oehler 35 Chrono-graph, temperature 35 deg, F. Group size average of two, three shot groups fired from sandbag rest.

Global Defense THOR XM408

“The .408 gives The preci-sion TacTical marksman a range advanTage over any .308 or .338 caliber rifle, while adding liTTle more To The weighT burden.”

— Continued on page 91

The sturdy steel detachable box magazine of the Thor is a single-stack unit. The standard unit holds five rounds, although an optional seven rounder is also available.

Sniper ready XM408 not only looks the part, but it shoots the part, too!

Doug Richardson Photos

90 TACTICAL WEAPONS • Jan. 2011 Jan. 2011 • TACTICAL WEAPONS 91

all previous methods took time. Leupold’s new RX laser rangefinders measure the angle and instantly indicate both the mea-sured distance and the exact ballistic dis-tance up or down so the precision tactical marksman knows the exact hold for precise target engagement. We believe this new rangefinder is one of the most significant recent developments in rifle shooting.

Tactical Glass Leuopold’s RXB-IV 9x32x rangefinding

binocular not only reads range to 1,500 yards/meters, but also has a built-in digi-tal compass with a declination setting for navigation. Most important however, is the ability of this binocular to determine true ballistic range, eliminating the need for a mathematical calculation when shooting up or down on an incline and combining tactical rangefinder and target acquisition binocular into a single unit. The RXB-IV dis-plays true ballistic range using an internal inclinometer. Ranging is automatic and when the binocular is in “scan” mode, range it is continuously updated as the user tracks a target or scans an area. There are no less than 13 different selectable reticles for just about any tactical situation.

Adaptive AccessoriesOf course, many engagements are in the

hours of darkness and the precision tactical marksman may be called upon to engage targets with little or no illumination. The current military standard night vision optic is Optical System Technology’s AN/PVS-22 UNS. It represents state of the art in image intensification (I²) night vision and is the U.S. military’s night vision optic of choice. The AN/PVS-22 can be used both as a hand held night vision optic and as a small-arms night sight.

Since the XM408 does not come with an extended MIL-STD-1913 rail for mount-ing night vision devices like the AN/PVS-22 above, we mounted our scope with a LaRue Tactical “STOMP” scope mount that clamps to any MIL-STD-1913 rail and encloses the scope in a metal cage, protecting it from physical damage while allowing full access to the windage and elevation knobs. The

LaRue mount also has a detachable canti-lever arm on top that allows the shooter to mount an AN/PVS-22 or similar night vision optic ahead of his day optic. There is a sec-tion of MIL-STD-1913 rail on top of the can-tilever arm to allow other accessories to be mounted. For the marksman whose rifle does not have a “long” MIL-STD-1913 rail to allow mounting a state of the art night vision optic like the AN/PVS-22, the LaRue mount is essential, allowing the optics to be mounted with no gunsmithing.

Shooting the XM408 brought no sur-prises. This rifle was well under sub minute of angle (MOA) accurate. The current test at only 100 yards confirmed the XM408’s accuracy. We fired two three-round groups that were essentially “cloverleaves,” with each round touching the others. Consider-ing the diameter of the .408’s bullets, that is a remarkable level of accuracy.

For more visit www.thorgdg.com.

EXTREME RANGE TESTFIRE»Cont inued f rom page 19

“we fired Two Three-round groups ThaT were essen-Tially ‘cloverleaves,’ wiTh each round Touching The oThers. considering The diameTer of The .408’s bulleTs, ThaT is a remarkable level of accuracy.”