Are you looking to use a 458 SOCOM upper receiver for your AR-15? That is understandable. However, this upper comes with a price. Building an AR platform rifle with the .458 SOCOM upper is not a particularly easy task when compared to putting together your run-of-the-mill 5.56×45 AR-15. There are fewer available components from the aftermarket resulting from the caliber’s lesser popularity. Regardless, a .458 SOCOM is a massive round with a power-packed delivery that is great for hunting or serious self-defense.
As we’ll discuss further in a minute, the .458 SOCOM round has horsepower similar to the vaunted .45-70 caliber, which places the .458 SOCOM squarely into the upper echelon of heavy-hitting modern sporting rifle calibers.
To begin, let’s review a few reasons you might consider sourcing a .458 SOCOM upper to enhance your arsenal.
Special Forces Applications
The .458 SOCOM was developed as a consequence of discussions around the perceived low hitting power that comes from the military’s standard 5.56 NATO round that so many of us shoot through the AR-15 platform. According to Wiki:
The .458 SOCOM came about from informal discussion of members of the special operations command, specifically Task Force Ranger’s experience that multiple shots were required to incapacitate members of the opposing force in Mogadishu during Operation Gothic Serpent. Many Somalis would chew the drug Khat all day and the effects of the drug would both curb their appetite (in a country plagued by famine) and increase their pain tolerance. Marty ter Weeme of Teppo Jutsu designed the cartridge in 2000 and Tony Rumore of Tromix was contracted to build the first .458 SOCOM rifle in February 2001.
The intention, as you can see, was to deliver
powerful massive shots that would level the enemy in ways that the 5.56 NATO never could. The conventional NATO 5.56 round just wasn’t cutting the mustard offensively when used in combat against drug-addled opponents, so the powers that be took an existing rebated-rim .50 Action Express case, lengthened it, and necked it down to accept the larger .458 diameter bullets. Original loads pushed a300-grain Barnes TTSX bullet out the huge hole in the muzzle at a cookin’ 1,900 fps for a resulting 2,405 ft-lbs of resulting energy. The whole works was designed to work with unmodified M16 magazines – but the 30-round 5.56 mags could only offer space for 10 of the roly-poly .458 SOCOM rounds. As the load was developed and gain a bit of traction, the commercial market started offering .458 SOCOM upper parts, and a couple rifle manufacturers offered .458 SOCOM single-shot, lever-action, and bolt-action rifles.
Great Against Big Beasts
If you happen to be a big game hunter, the power of the .458 SOCOM can enhance the terminal ballistics of your hunting rig drastically. The .458 SOCOM has been described by some as the ultimate “hog hammer” or “brush buster.” I already mentioned how it is like the .45-70 – a hard-hitting caliber many avid hunters in North America are already familiar with; it’s been on the firearms radar since 1873! The .45-70 Government was originally a black powder cartridge chambered in single-shot rifles. It is still considered by many to be a good round for any large critter that walks on four legs in North America; truly a big game cartridge.
Following in the .45-70’s hallowed footsteps, the .458 SOCOM slowly achieved recognition as an effective cartridge against heavy beasts like bears and even the heavyweight Russian boars. Thus, it is often utilized for self-defense in areas that have bears, tigers, and other animals that have the potential to turn the person holding the rifle into really surprised poop. So, if you happen to hunt or find yourself occupying the same general square footage asthese types of large animals, then a .458 SOCOM should certainly be considered as a great addition to your bullet-launching collection. Whether you’re going on a camping trip or a jungle safari, a built .458 SOCOM upper receiver has the potential to transform the power of your AR platform to suit needs ranging from pest control to stopping small charging busses. With the power of .458 SOCOM upper, proper bullet/load selection, and some actual skill, you shouldn’t need to worry about any threat in the wild, two- or four-legged. Within the effective range of the chosen projectile you have a monstrous weapon to take down elk, bears, moose, or any similar animal.
Power of a Big Bore Rifle in an AR Platform
While the .45-70 government round has massive power, it has a significant drawback – it mostly comes in rifles that are either single shot or lever action. These action types traditionally can be be a bit slower than a modern semi-auto sporting rifle. By integrating .458 SOCOM upper, you gain access to an equivalent level of power for the modern sporting rifle. You pack more theoretical damage capability and faster follow-up shots through the use of the AR’s semi-auto action.
Even More AR Options
If you decide to integrate a .458 SOCOM upper onto your existing AR, you will gain access to heavier projectiles than could ever fly from a 5.56 or even converting to a .300 Blackout. A 458 SOCOM upper opens you up to greater bullet diversity. As anyone who has owned an AR-15 long enough knows, the 5.56 ammo can be darn hard to come by depending on election cycles and other factors. Having a .458 SOCOM means you can obtain less popular bullets when you can’t buy (or want to conserve) 5.56. You know, if you ever actually see .458 SOCOM on the shelves. As a prepper, that is an important option to have.
The .458 SOCOM offers a wide array of projectile types – jacketed hollow points, full metal jacketed rounds, soft point hunting ammo, polymer-tipped ammo, subsonic rounds, and a whole variety of different caliber weights. Bullets of this caliber come in everything from 250 grains to a whopping 600 grains (yuuuuge!). If you want the greatest potential accuracy in a big caliber like this, many people may find the 250gr – 325gr range most suitable. With a slower 1:22 rifling twist rate, lighter bullets should be quite accurate – user skill and other factors notwithstanding. The more standard 1:14 twist rate is a likely better choice for bullets weighing 350 grains or more, to include subsonic loads.
A .450 SOCOM should be able to launch a 300 gain bullet at around 1900 feet per second, making it slightly slower than the .450 Bushmaster (about 2,100 fps with a 300 grain bullet) and .45-70 Government (about 1,900 fps with a heavier 350 grain bullet), placing the .458 SOCOM in the running for a modestly-recoiling gun that can really launch some big ol’ bullets. Where the .458 SOCOM would earn its keep is in the reliability department – its bottlenecked case will feed far more reliably than the straight-walled .450 Bushmaster.
Shhhh – Suppressors
Like the .300 Blackout, you have subsonic/silencer options with a .458 SOCOM. Suppressors for this caliber need a serious amount of volume and a big ol’ hole down the middle so if this is something you might want to incorporate, budget accordingly…a good can worthy of the .458 SOCOM will be pricey.
Just Plain Fun to Shoot
Think the 5.56 is fun to shoot? Wait until you throw one of these sledgehammers down range… and then another… and another. Need to smash some cinderblocks for no reason other than dramatic literary hyperbole? Hit them with the .458 SOCOM.
The Final .458 SOCOM Shot
Many modern .458 SOCOM uppers have a high level of durability (by necessity) and, typical of AR-15 upper receivers, Offer different barrel lengths and rail systems to optimize your build. Depending on how you prefer to configure your AR, you should be able to attach a red dot, optic, swanky muzzle device, and other essential accessories to your gun. A .458 SOCOM upper should be just as easy to customize as a standard 5.56mm upper; the barrel and bolt are the big differences; accessories are not.
Overall, if you decide to add a good .458 SOCOM upper receiver to your collection, you are opting for a serious upgrade in power. You will have the flexibility to customize the firearm combined with the ease of operating a caliber that offers dramatic horsepower from projectiles weighing up to 600 grains. All of these combined attributes makes the .458 SOCOM a worthwhile investment for an AR upper and a heavy hitter for the hunter, avid shooter, or firearm enthusiast.
Love the article! I’m a .458 SOCOM enthusiast already. With such a wide range of hand loading options it is really fun working up a variety of loads.
The 458 SOCOM is a blast to shoot. Depending on who you get your parts through you might need to do some fine tuning. I had an issue with double feeds with the first bolt I used but remedied that with a new Bolt Carrier Group(easier to acquire than a new bolt). I’d recommend getting frangible rounds for the fine tuning if you live in colder climates as it will be an easier sell to use at an indoor range. 350grains are just fun to shoot and a good bet to stop a coked out grizzly (or any other predator)in body armor.
I have purchased a Bear Creek Arsenal AR-15 side charging 458 socum. I new to the gun building aspect and am trying to find something along the lines of a Geissele Reaction Rod to utilize for a muzzle brake and/or future can. I had purchased a VISM vice block and found to my dismay it would work with the machining (I’m assuming attributed to the side charging platform). Does the end of a Geissele Reaction Rod match the configuration of the extension tube of the 458 socum? Is there another vendor who makes something along the lines of the Geissele Reaction rod specifically for a 458 socum? Any help / knowledge is certainly appreciated.
Great article…. While sorting my range brass I came across this monster short case.. After a bit of research I was hooked. Very cool round and amazing to just buy an upper and I have new addiction..