When it comes to guns, particularly those intended for severe stoppage, the development of the AR platform has witnessed a persistent trend toward increasingly capable and reliable designs. The AR-10 and AR-15 have long been the workhorses for a lot of military forces and civilian shooters as well, providing reliability, modularity, and simplicity. Yet as requirements change—whether for large-game hunting, protection from large predators, or performing demanding tactical duties—the demand for something with greater impact increases. That’s where the Big Horn Armory AR500 enters the picture, a gun that confidently pushes the boundaries of what an AR can accomplish by chambering the powerhouse .500 Auto Max cartridge.
The .500 Auto Max cartridge itself was the result of a relatively straightforward but ambitious concept: take the widely recognized .500 Smith & Wesson Magnum—a cartridge known for its potency—and redesign it as a rimless option that would be able to operate consistently in a semi-automatic rifle.
Big Horn Armory ran with that idea. What they came up with is a massive-bore round firing bullets weighing between 275 and 700 grains, with most factory options between 350 and 600 grains. It’s a cartridge that introduces raw, hard-hitting power into the AR platform without sacrificing function or manageability.
What’s more interesting about the .500 Auto Max is how versatile it is. This is more than simply a brute-force cartridge. It can deal with everything from hardcast projectiles for gamestopper work to hollow points for self-defense applications. Handloaders can tailor their configurations for any number of tasks—pest control out in the sticks, high-risk hunting, or even those tongue-in-cheek situations such as halting a runaway truck.
Creating a rifle strong enough to withstand this amount of force wasn’t an easy feat. The AR500 is based on an AR-10 platform but with extensive modifications, such as the bolt face being expanded for the .520-inch rim and very carefully re-engineered extractor and ejector systems to ensure continued smooth cycling. The barrel options are 10-inch or 18-inch length and are constructed of stainless steel with a 1:24 twist rate, also treated for extreme durability. Despite all that steel, the platform maintains the weight in check, under 10 pounds for most setups.
For all of its muscle, the AR500 does not neglect comfort and use. It features a free-floating M-LOK handguard, ambidextrous controls, and a crisp match-grade trigger with a pull of about 3.5 pounds. Recoil is certainly there, but it’s managed due to a well-designed muzzle brake. Consider more along the lines of a 20-gauge shotgun than a shoulder-smashing behemoth. The magazine system is smart too—single-stack, modified AR-15 magazines that feed the large straight-walled rounds reliably without a hitch.
On the ballistic end, the figures are awe-inspiring. A 440-grain bullet can travel at about 1,650 feet per second with more than 2,600 foot-pounds of energy—about three times that you’d find in a .44 Magnum. Heavier bullets can take it even higher. Like a 350-grain +P+ Buffalo Bore load that goes to 2,300 feet per second and brings with it a devastating 4,100 foot-pounds of energy. That’s enough to handle nearly any threat—animal or otherwise—with complete authority.
Accuracy isn’t an afterthought, either. Field testing indicates that with good optics, like a variable 1-8x scope, the AR500 can deliver tight 2-inch groups at 100 yards. Its flight remains relatively level out to 150 yards, and when it’s set in pistol mode with a 10-inch barrel and stabilizing brace, it’s small enough for in-vehicle carry or close-quarters applications. That makes it equally appealing to some military and security forces as it is to hunters and bushwhackers.
The platform also incorporates adaptability. An adjustable gas block guarantees smooth cycling whether you’re firing supersonic or subsonic ammunition, and it gets along well with suppressors as well. That degree of tuning only adds to flexibility, allowing the AR500 a place in anything from breaching and anti-material application to survival applications deep within remote areas of wilderness.
Taking the larger picture into account, the AR500 seems to be a logical evolution in the universe of AR platforms—a focused solution to particular problems. It doesn’t attempt to supplant 5.56 NATO or .308 Winchester for typical infantry duty, but instead establishes its niche for when maximum impact is required. It’s like how previous leaps in guns—such as from muskets to rifled barrels, or bolt-actions to semi-autos—brought additional aspects to what shooters and soldiers could do.
Standing behind this aggressive firearm is Big Horn Armory, a firm that’s committed to doing more than simply breaking rules. Their recent expansion—relocation to a larger facility in Cody, Wyoming, has enabled them to increase production, reduce wait times, and create additional jobs in the region. As told to Firearms News by company owner Greg Buchel, the expansion translates into more machines, more efficiency, and a deeper presence in the firearms market.
In a very real way, the AR500 embodies that spirit of innovation and expansion. It’s not merely an extremely potent gun—it’s a transformation of what the AR platform can achieve when pushed to its very limits. For those wanting unmatchable power in a readily familiar, user-friendly package, this may be the ultimate big-bore AR solution available.