Ruger AR-556 MPR 450 Bushmaster SA Rifle



  • Ruger AR-556 MPR 450 Bushmaster Multi-Purpose Rifle
  • (1) Magazine
  • Cable Lock
  • Owner’s Manual


Bushmaster Semi-Automatic Rifle

Introducing the new Ruger AR-556 MPR 450 Bushmaster SA Rifle (“MPR”) chambered in .450 Bushmaster. This new offering is ideal for hunting Midwestern whitetail deer and big pigs and target shooting at heavy steel.

The MPR platform offers superior accuracy, versatility and shoot ability by incorporating a Ruger® muzzle brake, Elite 452™ two-stage trigger, free-float handguard with Magpul® M-LOK® accessory attachment slots, and Magpul furniture. This new rifle combines innovative engineering, modern materials, and precision CNC-machining to make a superior rugged, reliable, semi-auto rifle chambered for the .450 Bushmaster cartridge.

Accuracy and velocity are maximized with a nitrided, 18-5/8″ cold hammer-forged barrel and the 11/16″-24 radial port muzzle brake to soften recoil. A carbine-length gas system with a 0.875″ gas block ensures reliable function and fits under the 15″ free-float handguard. The Magpul M-LOK accessory attachment slots around the handguard make attaching a sling and bipod easy. The handguard’s smooth profile situates easily on shooting sticks or a backpack for a steady shot. Ruger AR-556 MPR 450 Bushmaster SA Rifle

Engineered with a high-strength superalloy bolt and tapered lug geometry, the .450 Bushmaster MPR is built to withstand the strength of a cartridge that delivers twice the energy of 5.56 NATO. The upper receiver features a large window for easy ejection and is covered by a standard dust cover. Mil-Spec forgings are CNC-machined, anodized and finished with Ruger’s Elite 452 two-stage trigger, Magpul MOE grip and MOE SL® stock.

Ruger AR-556 MPR 450 Bushmaster SA Rifle

  • Lower receiver is fitted with Magpul® MOE® grip and MOE SL™ collapsible buttstock on the Mil-Spec buffer tube.
  • Handguard is free-floating for accuracy and the slim, 15″ length provides enhanced ergonomics and support.
  • Flattop upper receiver includes an enlarged window for easy ejection as well as forward assist, dust cover and brass deflector. CNC-machined from Mil-Spec forging and Type III hard coat anodized for maximum durability.
  • Bolt is machined from high-strength superalloy, more than 50% stronger than traditional MSR bolt materials, and engineered with tapered lugs to support the large case head of .450 Bushmaster ammunition. Ruger AR-556 MPR 450 Bushmaster SA Rifle
  • The Ruger® Elite 452™ AR-Trigger is a two-stage trigger that offers a smooth, crisp, 4.5 pound trigger pull. It features a full-strength hammer spring for consistent primer ignition and a lightweight hammer that enables a 30% faster lock time over standard MSR triggers.
  • Carbine-length gas system provides the most reliable function with .450 Bushmaster ammunition.
  • Magpul® M-LOK® accessory attachment slots along the 3:00, 6:00 and 9:00 positions with additional slots on the angled faces near the muzzle.
  • Cold hammer-forged 4140 chrome-moly steel barrel with ultra-precise 5R rifling and black nitrided finish provides exceptional accuracy, longevity and easy cleaning. The 1:16″ twist rate maximizes accuracy with bullets ranging from 170 to 260 grains.
  • Chrome-plated bolt carrier inside diameter and chrome-plated gas key inside diameter provide exceptional resistance to hot gases. The gas key is staked so that it will not loosen after extensive firing. Ruger AR-556 MPR 450 Bushmaster SA Rifle.
  • Ruger® muzzle brake is a radial port design that significantly reduces felt recoil and muzzle movement. The 11/16″-24 threaded barrel allows for standard muzzle accessories to be installed.
  • Also includes: One, 5-round metal box magazine.
  • Model Number: 8522
  • Caliber: 450 Bushmaster
  • Stock: Black Synthetic Collapsible
  • Handguard: Free-Float M-LOK®
  • Sights: None
  • Barrel Length: 18.63″
  • Thread Pattern: 11/16″-24
  • Twist: 1:16″ RH
  • Capacity: 5
  • Finish: Type III Hard Coat Anodized
  • Ruger AR-556 MPR 450 Bushmaster SA Rifle
  • Height: 7.30″
  • Weight: 7.4 lb.
  • Overall Length: 35.60″ – 38.90″
  • Length of Pull: 11.10″ – 14.40″
  • Grooves: 5


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