Magazine release button interference pin assembly and AR-style lower receiver functions to prevent the depression of the magazine release button on an AR-style rifle while the upper receiver is closed or locked onto the lower receiver. Magazine release button interference pin assembly and AR-style lower receiver prevents magazine release and reloading while the upper receiver is closed or locked onto the lower receiver. Magazine release button interference pin assembly and AR-style lower receiver is a magazine release button interference pin assembly as well as a specially machined lower receiver to accept the magazine release button interference pin assembly. Magazine release button interference pin assembly includes a special magazine release button interference pin with at least two protrusions, a spring, and a retaining pin.