Ruger AR-556 .450 Bushmaster 18.63″ Rifle

Description

The Ruger AR-556, .450 Bushmaster, 18.63″ Barrel, 5rd, Black is a purpose-built AR-platform rifle chambered for the hard-hitting .450 Bushmaster cartridge. It’s designed for hunters and shooters who need serious stopping power at short to medium ranges, offering a reliable, no-fuss platform for big game or heavy brush. I’ve put a few boxes of Hornady Black through this one, and it’s a thumper that gets the job done without drama.

Key Features

• Chambered in the powerful .450 Bushmaster cartridge for maximum energy transfer.
• 18.63-inch cold hammer-forged barrel with a 1:16 twist rate, optimized for heavy .45-caliber projectiles.
• Ruger’s patented two-stage trigger for a crisp, predictable break.
• Ruger Elite 452 AR-15 trigger guard for use with gloved hands.
• M4-style collapsible stock and standard AR-15 pistol grip for a familiar, adjustable feel.
• Includes one 5-round magazine, keeping it compliant for hunting regulations in many states.

Specifications & Details

Caliber	.450 Bushmaster
Barrel Length	18.63″
Twist Rate	1:16″ RH
Overall Length	35.5″ – 38.75″ (adjustable)
Weight	6.8 lbs
Magazine Capacity	5 Rounds

Here’s the thing—this isn’t a plinker. The .450 Bushmaster round is a serious piece of hardware, generating significant recoil and muzzle energy. The rifle’s design handles it well, with a solid feel and a gas system tuned for reliability. At just under 7 pounds, it’s maneuverable in a blind or thick cover. The price point of $1064.82 puts it in a competitive spot for a factory-built, big-bore AR. It’s mil-spec compatible where it counts, meaning you can swap out the handguard or stock with a wide array of aftermarket AR-15 parts if you want to personalize it later.

Who This Rifle Is For

This Ruger is built for the hunter. Specifically, it’s for hunters in states with straight-wall cartridge regulations or those pursuing medium to large game like whitetail, boar, or bear at ranges where a .223 might lack authority. It’s also a solid choice for a dedicated home defense tool in rural areas where over-penetration is less of a concern than sheer stopping power. If you want an AR but need more thump than 5.56mm can provide, this is your direct path.

Pros & Cons

Pros: Delivers massive downrange energy in a familiar, reliable AR platform. The cold hammer-forged barrel promises longevity and consistency. It’s a complete, ready-to-shoot package from a trusted manufacturer—no gunsmithing required. The 5-round mag keeps you hunt-legal without fuss.

Cons: Ammunition is more expensive and less common than 5.56mm. Recoil is stout—manageable, but noticeably more than a standard AR. The proprietary .450 Bushmaster magazines are required; standard PMAGs won’t work. That said, the performance trade-off is the whole point.

Frequently Asked Questions

Q: Will this upper fit on my existing AR-15 lower receiver?

A: Yes, with a major caveat. The .450 Bushmaster cartridge requires a specific bolt carrier group and magazine. This complete rifle has them, but if you’re buying just an upper, you must pair it with a .450-specific bolt and mags. The lower itself is standard mil-spec dimension.

Q: Is the .450 Bushmaster a good deer cartridge in Missouri?

A: Absolutely. It’s an excellent choice for Missouri whitetail, especially in the timber or for longer shots across fields where a slug gun might fall short. It meets straight-wall cartridge requirements in many states and carries energy effectively out to 250 yards.

Q: What optics work well on this rifle?

A: Given its hunting role, a low-power variable optic (LPVO) in the 1-6x or 1-8x range is a perfect match. Brands like Vortex, Primary Arms, or Leupold offer great options. A robust red dot like an Aimpoint PRO is also a solid choice for fast, close-range work. The Picatinny rail is ready for whatever you choose.

This Ruger AR-556 in .450 Bushmaster is a straightforward, powerful tool that does one job very well. It’s available at firearms-missouri.com for Missouri residents and nationwide. If you’re ready to step up to a big-bore AR, this is a reliable place to start.