This article originally appeared in RECOIL ISSUE 37
Photos by AZPhotoMan and Steven Kuo

PHEONIX WEAPONRY PUTS A NEW SPIN ON A FRONTIER CLASSIC WITH THE .45-70 AUTO

It wouldn’t be much of an irrational argument to claim that the AR-15 platform has been refined nearly to its engineering apex. Different manufacturers have made alterations to barrel length, gas system length, buffer weight, buffer spring weight, gas port size, chamber dimensions, and just about any other physical dimension you can name. With the sheer volume of technical data now available on the rifle’s performance in various configurations, America’s Rifle has now become a prime test bed for all manner of ballistic experiments. In a quest to push the performance envelope of the platform, and to sell more rifles, many companies are fielding AR-pattern rifles in more and more unconventional calibers for specialty applications.

Enter Phoenix Weaponry in Colorado. They’ve undertaken a number of outside-the-box projects and are bringing a particularly unique big-bore AR to market. What started as a pet project will now be available for purchase. They’ve built a highly customized AR rifle around an equally custom cartridge: the .45-70 Auto. Phoenix Weaponry let us play with their preproduction test rifle during a group hog hunting trip in Texas. The rifle’s performance against the Lone Star State’s four-legged vermin didn’t disappoint. Before we talk about that, a little history on where this hard-hitting round came from.

What's Old is New Again
The renaissance of American small arms development that occurred during and after the Civil War gave birth to a number of innovations in the realm of shoulder-fired ballistics. Some of these wound up relegated to the pages of firearms oddity. Others turned out to be true milestones in the history of firepower. Most fell somewhere in between. The .45-70 cartridge was developed by the U.S. Army’s Springfield Armory specifically for use in their 1873 Trap Door rifle. The original full nomenclature for the cartridge, 45-70-405, was derived from the load parameters — a .45-caliber slug, sitting atop 70 grains of black powder, weighing 405 grains.

The cartridge was a replacement for the earlier .50-70 cartridge that was, from its outset, a temporary solution for Army requirements that saw less than a decade of service in the ranks. The smaller .45-caliber cartridge was flatter shooting with a longer range compared to its bigger, short-lived brother. Note that “flatter shooting” is used with a large dash of relatively speaking. The combination of a heavy slug and slow-burning black powder gave the .45-70 a rainbow trajectory.

From left to right: .45-70 Auto, .308, and .223.

While making accurate hits at long range was possible, and did occur with some regularity, this was heavily dependent on proper range estimation and sight adjustment, as the original loadings could generate as much as 50 inches of bullet drop by the 400-yard line. Minimum acceptable accuracy standards for the .45-70 set forth by Springfield were a 4-inch group at 100 yards, but it’s said that a more accomplished marksman could hit a 6×6-foot square out to 600 yards — a technique mainly used in mass volley fire, as the effective range on point targets was capped at 300 yards. Original loadings pushed the aforementioned 405-grain bullet out of the muzzle around 1,300 feet per second.

The .45-70 saw service across the western frontier throughout the entirety of the Indian Wars. In this capacity it gained an excellent reputation against both enemy forces and large game. Its military service continued into the Spanish-American War, when the Army finally realized that its soldiers were severely outgunned against an enemy with bolt-action repeating rifles. The U.S. Army had previously chosen the Trapdoor Springfield over available repeating designs, which the brass deemed wasteful of ammunition and encouraging inaccurate fire. An interesting piece of military trivia — the .45-70 can still be found aboard U.S. Navy ships, in the form of blank cartridges used for line-throwing guns.

As a result of its successful performance on the plains, the .45-70 gained popularity among sportsmen and hunters of the time, with some medium and big game hunters using it even today. The almost-one-ounce lead pill has proven effective against traditionally difficult game, including elk, buffalo, and grizzly bear. Because of this, several companies produce modern ammunition and repeating rifles for the round. Lever-action carbines have been a staple guide gun among Alaskan bush hunters and others who routinely encounter potentially aggressive large animals.

Since the original .45-70 cartridge sported a thick rim for breach loading rifles, Phoenix Weaponry had some work to do in order to fit the round into a box-fed autoloader. What they wound up doing was to use a lathe to turn down the rim on genuine .45-70 brass. The result is a rimless case that’ll fit on an AR-10 bolt face. While no commercially loaded ammunition is currently available, you have two options to roll your own. If you already have a lathe to modify original .45-70 brass, Phoenix will sell you the form cutter. Or you can simply purchase pre-modified brass directly from them.

Since we didn’t have any loading materials on hand, they pre-loaded some test ammo for us. These rounds used a 325-grain Hornady FTX slug atop 53.5 grains of IMR4198 powder. For reference, similar .458 SOCOM loadings use only 36 grains of the same fuel. Resulting muzzle velocities out of an 18-inch barrel were in the neighborhood of 2,500 feet per second. The crew at Phoenix has several other loads either already dialed in or in the works, including a 250-grain FTX bullet traveling at 2,700 feet per second and a 500-grain DGX slug that, at time of writing, had yet to be chronographed.

THE LAUNCHER

While the .45-70 Auto was designed to run off an AR-10 bolt, and the rifle looks like an AR-10 from the outside, much of the rifle is produced in-house. The receiver set, dust cover, handguard, trigger, and muzzle brake are all produced by Phoenix Weaponry. The muzzle brake is what they call their chevron brake. We found it to be highly effective and highly loud. Noise, flash, and fireball are all exactly what you’d expect from sending a ¾-ounce slug down range at Mach 2.

The trigger on the test-bed rifle tripped at just over 3 pounds with a touch of pre-travel before a crisp break. The handguard is also made in-house. Rail sections, sling mounts, and hand stops can all be mounted to it. Having said that, we’re not sure why it wouldn’t have been simpler (and more convenient for the customer) to make an MLOK pattern tube. It’s 15 inches long, shown here on an 18-inch barreled gun. Speaking of barrels, it’s interesting to note that this rifle runs a 1:14 twist barrel, while original .45-70 rifles typically used a 1:20 twist — logical, considering the increased velocities out of the autoloader. The barrels themselves are 4140 CMV and button rifled.

Phoenix uses a mid-length gas system on the 18-inch rifles. If you request a 20-inch or longer barrel, it’ll be a rifle length system. The BCG, buffer, and buffer spring are all standard AR-10 parts, which means owners will be able to tune their recoil systems to a specific load. Additionally, the charging handle, furniture, and fire controls are off-the-shelf as well. Feel free to add on your favorite bolt catch, mag release, or selector lever.

Magazines start life as standard AR-10 boxes, but must be heavily modified by Phoenix Weaponry to actually feed the .45-70 Auto round. We asked about the modifications, but they’re playing that process tight to the vest. Once complete, you’ll get 6 rounds of .45-70 into a 10 round PMAG. We’re waiting patiently for them to perfect drum mags. Our test gun was cerakoted in FDE, but since these weapons will be made to order, you’ll be able to request the color or camo pattern of your choice.

ROUNDS DOWNRANGE

We had the opportunity to take this gun out into the (hog) killing fields of west Texas during a team building hunt with Escondido Hunting at the scenic Quintanilla Ranch in Tilden, Texas. If you’ve never heard of Tilden … don’t worry … neither has anyone else. But the food was good, the people were great, and it let us witness firsthand the potency of 19th century ballistic genius. On the flat range, we were zeroed within five rounds. Our gun came with a Burris MTAC 1.5-6x42mm already mounted, which made things pretty easy at 100 yards and in. We also learned very quickly that this is not the gun you want to be shooting under a covered shooting position with people on either side of you — unless you hate those people.

Recoil wasn’t nearly as stout as expected. The monster muzzle brake, softer-shooting mid-length gas system, and buffer/spring combination brought it down to a level that we would compare to an inertia-driven 12-gauge. Follow-up shots were definitely possible, though had to be executed judiciously.

We did get lucky enough to take a single small hog with this rifle. It was after sunset, and we didn’t have night vision. After hours of no activity, the author and RECOIL OFFGRID web editor Patrick McCarthy was getting ready to pack it up for the night when they heard movement outside the blind. The shot was made through the MTAC’s illuminated reticle with Patrick using his EDC flashlight to illuminate the trio of hogs approximately 60 yards from the blind.

The shot was far from ideal, catching a 40-ish-pound pig in the hindquarters. A smaller gun would’ve left the animal suffering. But at twice the speed of sound and then some, the 325-grain flex tip slug ended the ordeal in a matter of seconds — inverting the pig’s entire back end in the process. When the two of us, our guide, and Iain inspected the crime scene, the results were impressive to the point of being almost comical. Suffice to say that .45-70 Auto can be loaded to handle almost anything in the lower 48.

The only limiting factor is price point. This rifle is listed on Phoenix Weaponry’s website at $4,800, a price tag that hits almost as hard as the .45-70 itself. We concede that there’s a lot of custom tuning that goes into getting these guns to function properly. But a price point that’s halfway to five figures will make this gun a big-bore pipe dream for many. Those with the means, however, will get reasonably close to aircraft-grade firepower and be hard pressed to find themselves underpowered in any situation.

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