Ruger BX-1 10/22 22 LR Magazine 10 Rounds Black Polymer review offers the following information; Crafted from lightweight polymer with steel-reinforced feed lips, BX-1 magazines designed to endure extreme conditions and keep on feeding every single time. America’s most popular rimfire rifle for over half a century, the Ruger 10/22 is an iconic firearm that you probably already own. These BX-1 magazines were designed in-house by Sturm Ruger & Co. to go along with other BX series upgrades and elevate the average 10/22 into something even better.