Ruger SR-556FB 5.56x45mm NATO 223 Rem.

Ruger makes some well-known semiauto rifles, including the 10-22 22 LR and the Mini-14. But when the company rolled out the SR-556 in May 2009, it was the company's first foray into an increasingly crowded and competitive segment. And just looking at the feature set, including the two-stage piston-driven action, shows us the company put a lot of careful thought into the initial build.To begin: The SR-556FB had a heavy contour, 16.12-inch chrome-lined barrel forged from Mil-Spec 41V45 chrome-moly-vanadium steel. The 0.700-inch-thick barrel had a 1:9 twist rate and was capped with an AC-556 flash suppressor. Our testers preferred the closed-bottom design of the other two guns' hiders because they're less likely to kick up debris if the shooter is on the ground. Chambered in 5.56mm NATO, the Ruger SR-556 also fired 223 Rem. ammunition.

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I saw a fellow with one last year just as they were introduced. His ripped the rim off of several cases, leaving the case in the chamber.