AllTerra Arms Mountain Shadow Carbon Rifle

Presentation goes a long way in creating a positive feel for a brand, but it can also prove entirely practical. Unboxing an AllTerra Arms rifle certainly makes an impression. My test rifle arrived in a quality hardcase, one of those roto-molded numbers you can jump up and down on without the slightest worry of harming the contained rifle. The case includes steel-reinforced lock hasps, folding handles all-round, molded/steel-pin hinges and roller wheels. Unsnap the four latches and the awe factor is further elevated by red-on-black closed-cell foam custom cut to hold the rifle, bolt, ammunition and other accessories. The black top foam lid liner includes a cut AllTerra Arms logo accented in red. It’s pretty impressive, but also practical in that the rifle is well protected.

Contained within is one of AllTerra’s modern works of firearms art. In this case, the 5.9 pound (bare) Mountain Shadow Carbon, the company’s finest hunting-specific rifle. First impressions included a heavy carbon-wrapped barrel with a gullwing-slotted muzzle brake, sleek carbon fiber stock – the carbon weave showing through an ultra-thick clearcoat infused with subtle grey-green “Damascus Zombie” camouflage – highlights the long skeletonized bolt handle and spiral-fluted bolt body. The trigger guard and hinged drop plate are milled aluminum, the stock holds a five-slot length of Picatinny rail. The test rifle arrived with a Zeiss Conquest V6 3-18x 50mm scope set in twin Talley one-piece base/rings.

But this was all immediate aesthetics, at least to any hunter who has spent time pursuing wild sheep or alpine mulies. It is the kind of ultra-modern rifle some hunters might find, well, somewhat industrial.

But the real appeal lays in AllTerra’s promise of very serious accuracy – besides being a rifle that is 100 percent designed, engineered and manufactured in Boise, Idaho. AllTerra offers an absolute money-back performance guarantee: sub-half-inch three-shot, 100-yard groups with premium factory ammunition; sub-quarter-inch three-shot, 100-yard groups using AllTerra Arms custom loads. Proof targets are provided with every rifle, the 6mm Creedmoor tested here arrived with three targets holding three-shot groups measuring from .190-inch (90-grain Lapua Scenar-L AllTerra handload) to .305-inch (Hornady Match 108-grain ELD Match factory load), center to center.

Further, AllTerra promises buyers will experience no significant change in accuracy when shooting different bullet weights and their rifles will cycle smoothly under all conditions. Buyers have 90 days to make this determination, with a full refund given to anyone who is dissatisfied with the results. But then, AllTerra employs former military snipers, professional shooters and firearms instructors to do this bench shooting and certify rifles are delivered that meet the company’s accuracy assurances. If you’re not a former military sniper, professional shooter or firearms instructor, assembling such groups may prove challenging. I know I felt intense pressure during testing to match AllTerra’s results.

Founded by Andrew Foster in 2015, AllTerra’s entire reason for being was to create super-accurate and 100 percent reliable rifles. Foster started by first analyzing current bolt-action designs and eliminating what he felt were inherent flaws. Two years of Research & Development, many prototypes, meticulous quality control and utilizing only the best materials currently available, ultimately resulted in rifles bridging the gap between benchrest accuracy and hunting reliability.

Foster completely redesigned the process of bolt-face-to-barrel interface and barrel-to-receiver alignment. Patented Convergence action technologies brought these goals together. Everything from the custom firing pin to the ergonomic one-piece billet bolt was engineered for accuracy and reliability.

The basis for all AllTerra Arms rifles is the Convergence Series action, including No-Fail Cycling, Bolt-to-Bore Alignment and Dual Lock Barrel Seat technologies. The receiver is milled from a single piece of hardened 416 stainless steel weighing 8 pounds and including an integral recoil lug. The roughed-out receiver weighs 1 pound. A small pilot hole is then drilled through the receiver’s exact center. An EDM machine with an electrified wire is then used to cut metal to a concentric center. After the EDM process, AllTerra Arms machining technology finishes the receiver interior. The removal of the receiver’s center mass is formed with .0005-inch accuracy, resulting in a dead-nuts centered bolt shroud and lug raceways. Eight CERAKOTE metal finishes are offered, and the test rifle done in a tasteful Graphite.

The bolt is cut from a single piece of 4140 chromoly steel, using careful engineering and precision machining to align the bolt perfectly and eliminate bolt binding, while also ensuring a tight bolt lock. This also leaves the firing pin perfectly aligned for a consistent center primer punch. AllTerra bolt lock time is enhanced first through “smarter, faster firing pins.” The firing pin spring floats inside the bolt center – instead of “snaking” under tension and rubbing against the inner surfaces. This helps the fluted firing pin ferrule move faster upon triggering, particularly in cold weather. Added to the dead-center pilot hole, this produces nearly instant lock time. The safety is a basic Remington-style push forward to fire, pull back to engage system. The test rifle’s trigger was a superbly crisp TriggerTech Primary, which broke around 2 pounds without overtravel. Three Timney and three TriggerTech options are offered in all models.

AllTerra bolts are also impervious to binding, even when dirty or subjected to gritty brass. AllTerra machines relaxed tolerances between the bolt and receiver so debris is cleared during cycling to eliminate binding. The bolt includes a deep spiral fluting to shave weight and the body is given a nickel boron treatment for added durability and slicker cycling. The patented conical lugs, engaged and locked into a patented elliptical raceway, also offer self-cleaning, nonbinding cycling. The skeletonized bolt handle extends to a hexagonal head located just to the right of the trigger. The left-side bolt release is a spring-loaded rocker without knurling. A Mini M16 extractor and dual ejectors fling fired cases well clear.

AllTerra’s patented Dual-Lock Barrel Seat starts with 20-pitch threads (instead of less precise 16-pitch) and finishes with two precisely machined seating rings fore and aft of these threads. The seating rings nest into two seating sleeves machined into the receiver, forming a solid and precise mating between receiver and barrel. This also produces a balanced harmonic pattern and AllTerra’s zero-tolerance “bolt-to-bore” alignment.

AllTerra solves bore alignment inconsistencies by center drilling, followed by a boring bar that cuts concentric to the bore. This removes most of the steel for chamber cutting, but not all. The bore is then finished with the chamber reamer to concentric and axial tolerances of .0001 inch. Initially, only match-grade barrels are chosen, which are then hand-lapped to a mirror finish – including the lightweight shrouds housed in wrapped carbon barrels like the one tested here. Finally, the bore crown is fine-tuned for balanced ballistics.

The Mountain Shadow Hunter is offered in 13 cartridge choices from 6mm Creedmoor to .338 Sherman Short. These include some exotics like the 6.5mm, 7mm, .300 and .338 Sherman Short, 6.5 Sherman Short Tactical and 7mm SAUM, newer rounds like the 6.5 and .300 PRC, 6.8 Westerner and .28 Nosler, plus several classics like the .308 Winchester and 7mm Remington Magnum.

The Carbon Hunter ultralight stock utilizes six layers of premium carbon fiber for strength, light weight and vibration dampening, with geometry tailored to align the shooter’s body and eye straight over the bore centerline. The above-centerline heel routes recoil straight back to be spread evenly across the recoil pad, without undue muzzle jump or stock torque. The stock includes a 24-ounce base weight and a negative cheek comb for intuitive scope/eye alignment while maintaining a solid and repeatable cheek weld. The stock is pillar bedded. The tilted palm swell encourages comfortable wrist positioning that reduces pre-shot canting and recoil torque, while also providing optimal trigger reach for more controlled squeezes. The subtle beavertail forend promotes a comfortable forward grip and the molded texturing allows good purchase when wet or while wearing gloves. The molded-in camouflage schemes won’t chip or flake. AllTerra offers 11 color schemes, .50-, .80- or 1-inch-thick recoil pads and standard length of pulls (LOP) from 12.5 to 14 inches. Custom lengths are available and a multitude of sling/accessory attachment options are offered.

The five-slot Picatinny rail with a QD socket is a welcomed addition, as I seem to collect bipods. The AllTerra milled-aluminum drop plate is released by a knurled tab located on the inside of the metal trigger guard. Names or artwork can be added on request, or a detachable mag system chosen. Overall, the stock was quite comfortable at the provided 13½-inch LOP.

The fully-floated, match-grade, hand-lapped carbon barrel measured 22 inches long and .90-inch just behind the 5⁄8-24 muzzle threads. It included an AllTerra ultralight muzzle brake. Lengths of 20 or 22 inches are offered. The barrel had very little taper and included a 1:7.5 twist rate perfect for launching heavier, long-for-caliber 6mm bullets suited to long range work. This would be my first experience with a carbon-wrap barrel, which I found heated slowly and cooled quickly.

AllTerra also offers scoped packages, including big-game and long-range optics from Leupold, Nightforce, Steiner, Swarovski, Kahles and Zeiss, all set in Talley hardware. The 3-18x 50mm Zeiss Conquest V6 set in four-screw Talley base/rings seemed a natural fit for this rifle, providing some long-range reach without becoming excessive during backcountry treks. The 30mm scope included exposed windage and elevation turrets and side parallax adjustments in a welcomed second focal plane (SFP) arrangement. The custom case the test rifle arrived in is a $350 option.

One of the unique aspects of AllTerra rifles is its ability to wring impressive accuracy from a wide variety of ammunition and bullet weights. This bore out during load testing, using not only the fine-tuned ammunition provided by AllTerra’s team, but premium factory loads from Hornady, Berger and SIG Sauer, plus several handloads proven accurate from my own 6mm Creedmoor rifle (Ruger Precision Rifle with a 26-inch barrel). Factory ammunition tested included Hornady’s Varmint Express loaded with 87-grain V-MAX, Berger Ammunition’s 95-grain Classic Hunter, SIG Sauer’s Elite Hunter with 100-grain Controlled Expansion Tip bullet and Berger Ammunition’s 105-grain Hybrid Target. My handloads included Hammer Bullets’ 88-grain Hammer Hunter paired with 43.5 grains of IMR-4451; Nosler’s 105-grain RDF with 43 grains of Shooters World 4350; Berger’s 108-grain Elite Hunter with 45 grains of Vihtavuori N565; Hornady’s 110- grain A-Tip with 39.5 grains of Alliant Reloder 16 and Nosler’s 115-grain RDF with 44 grains of Vihtavuori N560. The handloads supplied by AllTerra held 90-grain Lapua Scenar-L bullets seated over 42.1 grains of Hodgdon H-4350.

Testing started badly, as a lengthy setup followed by a full-out, mid-May snowstorm complete with biting wind. I also found my pet 6mm Creedmoor loads included overall lengths a touch too long, indicating my rifle has a bit more freebore than the AllTerra. I returned to the loading bench and awaited fairer skies.

Straight up, I was unable to duplicate the groups shot by AllTerra’s guys, though I tried mightily. AllTerra supplied 40 of its tailored loads, though my best group printed only .37 inch, most hovering in the .4s and .5s. Blame it on different altitude, temperature, relative humidity, rest dynamics, wind… I mostly blamed myself. But then I shot .28- and .22-inch groups with my own handloads. The .28-inch group involved 43 grains of Shooters World SW-4350 under a Nosler 105-grain RDF at 2,929 feet per second (fps); the .22-inch group with 45 grains of Vihtavuori N565 under a 108 Berger Elite Hunter at 2,880 fps. The AllTerra didn’t care for the Hammer Bullet, or the heaviest bullets tested.

Factory ammunition proved a little more consistent, with groups of .50-inch (Hornady 87-grain Varmint Express), .52-inch (Berger Ammunition 95-grain Classic Hunter), .64-inch (SIG Sauer Elite Hunter 100-grain Controlled Expansion Tip) and .57-inch (Berger Ammunition 105-grain Hybrid Target).

AllTerra accuracy comes at a price, obviously. The rifle as tested includes a $5,995 base price, plus added accessories, custom finishes and scope and mounts. This one rang up at more than $8,300. It’s certainly easy to build a cheaper rifle, but not one that matches this level of consistent accuracy. Though I couldn’t duplicate AllTerra’s results, I was still duly impressed.