The Ruger 10/22 is one of the most prolific semi automatic rimfire rifle in history. The rotary style BX-1 10rd .22lr magazine has proven itself over the years to be an incredibly realiable design. Made from very tough, lightweight polymer with reinforced steel feedlips for added durability. The steel spring and polymer follower work to feed any type of ammunition without fear of a magazine related malfunction. If you have a Ruger 10/22 .22lr and aren't shooting with genuine Ruger 10/22 BX-1 magazines, then you are missing out on the best magazine for your rifle that you can own.