For 2019, Ruger has introduced a new model of its popular AR-556 MPR chambered for the straight-walled .450 Bushmaster cartridge. The bolt is machined from high-strength superalloy, which Ruger says is more than 50 percent stronger than traditional MSR bolt materials, and engineered with tapered lugs to support the large case head of .450 Bushmaster ammo. Additional features include a 18.63-inch cold hammer-forged 4140 chrome-moly steel barrel with ultra-precise 5R rifling and a black nitrided finish provides exceptional accuracy, longevity and easy cleaning. The lower receiver is fitted with a Magpul MOE grip and MOE SL collapsible buttstock on the Mil-Spec buffer tube. Ruger's 15-inch free-float handguard is designed to be light, stiff and versatile, and Magpul M-LOK accessory attachment slots sit at the 3:00, 6:00 and 9:00 positions. MSRP: $1,099; ruger.com.