Upper Receivers and Lower Receivers can significantly increase your rifle’s performance because of the quality. They will add a unique, customized look to your AR-15 because of their style. Most of the receivers we offer at RW Arms feature premium-grade materials so that you can trust the quality. We support manufacturers that are built here in the USA. The tolerances and specifications of the mil-spec feed rams can work with various mil-spec lowers. Aftermarket receivers are a vital addition to any custom build. Most will function and work with any standard Mil-Spec lower receiver on the market.