Rock Island Rock Ultra FS 45 Auto (ACP) 5in Black Parkerized Pistol - 8+1 Rounds - The Rock series is Rock Island Armory's most well-optioned line of 1911 pistols built in the traditional 70 series design with the addition of next level upgrades. Like all Rock Island 1911s, each is built using 4140 ordnance steel on the industry's best CNC machines while being hand-fitted and tested to strict tolerance guidelines for unmatched quality and value.