458 SOCOM AR Rifle – Rock River Arms LAR-458 AR15 – .458 Caliber

The Salt Rifle Club by The Trunnion reviews the big daddy 458 SOCOM and its ballistics, and compare it to other AR designed calibers including the 50 Beowulf, the 450 Bushmaster, the 6.8SPC and the .223/5.56. We also test the .458 SOCOM’s explosive power in the Rock River Arms LAR-458 AR 15 against wood boards and bricks using Underwood , Great Lakes and Swift ammunition.

“Inspired by the lack of power offered by the 5.56 NATO cartridge used in the M4 carbine and the M16 rifle, the .458 SOCOM came about from informal discussion of members of the special operations community, specifically Task Force Ranger’s experience that multiple shots were required to neutralize members of the opposing force in Mogadishu during Operation Gothic Serpent. 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. Tony Rumore fired the very first round of .458 SOCOM ammunition in the Tromix shop located in Broken Arrow, Oklahoma on February 16, 2001, at 8:30pm.”

The 458 SOCOM “was designed to be 100% compatible with the M4 platform. This included the buffer, buffer spring, GI magazines, many aftermarket .223/5.56 magazines, and magazine well. In .223/5.56 caliber, cartridges stack in a staggered (double stack) fashion. However, with the much larger .458 SOCOM, rounds “single stack” without any modification to the standard GI magazine feed lips or follower, making it the most versatile and cost effective big bore offering in an AR-15 platform. A standard 20-round 5.56mm NATO magazine can hold seven .458 SOCOM rounds and a standard 30-round 5.56mm NATO magazine can hold ten .458 SOCOM rounds.”

“Today, .458 SOCOM rifles and complete upper halves are available from Rock River Arms and Tromix. Disappear Gear and Wilson Combat offer barrels and uppers although they do not use designer-copyrighted reamers and functionality may be compromised. Barrels and bolts can be purchased from Southern Ballistic Research and Tromix. Because this round has not been accepted as a SAAMI standard round, brass for hand loading is exclusively produced by Starline. Loaded ammunition is also manufactured by Southern Ballistic Research, Cor-Bon, in addition to several smaller boutique loaders.” Wikipedia.

“Rock River Arms is owned and operated by brothers Mark and Chuck Larson. Between 1981 and 1991 the Larsons worked at Springfield Armory, Inc., where Mark was the head armorer. From Springfield Armory, the Larsons went into partnership with Les Baer to form Les Baer Custom and build custom 1911 pistols. Parting ways with Les Baer in 1993, the Larsons began to build AR-15 type rifles for Eagle Arms in Coal Valley, Illinois. At around the same time, they began their own venture, Tolerance Plus (the name was later changed to Rock River Arms), producing custom 1911 pistols. The Larson brothers severed their connection with Eagle Arms in 1997 when that firm moved to Geneseo, Illinois.[4] At the same time, Rock River Arms began to build AR-15 style rifles. For a time, Rock River Arms produced M1911 pattern pistols in addition to rifles, however eventually they dropped that line and now focus their production exclusively on AR-15 pattern rifles.” Wikipedia.

If Wyatt Earp and Wild Bill Hickok were alive today . . .

13 thoughts on “458 SOCOM AR Rifle – Rock River Arms LAR-458 AR15 – .458 Caliber”

  1. 458 SOCOM was developed after US military had issues in Aphganistan (2003) with enemy combatants surviving hits with 556 rounds. This is not a hunting round per se but is very effective on wild bore etc. The energy transfer and wound channel inflicted by this round ensures the first hit is fatal on a human. This round did not penetrate all the way thru the wood or bricks because it was designed to shed a lot of its energy on impact via deformation which also inflicts a large wound channel. Human flesh is nowhere near as robust as 4 inch thick wood. You get hit with this round it's game over….

  2. How's the reliability of the RRA 458? There have been a lot of mixed reviews where they don't like the polymer mags and stove pipe issues regardless of what mags or ammo you feed it. Any input?

  3. bases on what i see, the 458 doesnt have the penetration power. That big round with the energy they say it have, should have disintegrated all the wood and bricks. i won't waste my money on it.

  4. you did see the bullet, fully expanding, bouncing off the bricks and landing between bricks/wood, then rolling back up range, right? pretty easy to see

  5. I don't really understand why did they have to develop a new round.. realistically 7.62×51 will do very similar damage at close range and you still have the ability to make long range shots.. this reminds me of the Russian 9×39, but of course russian round not nearly as powerful and fast.. for supression purposes. But overall idea of big fat bullet in a rifle casing is similar.

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