A receiver is configured to receiver a tabbed magazine. The receiver includes a receiver well having a slot configured to accept the tab on the tabbed magazine. In operation, the tabbed magazine can be inserted into the receiver well without having to rotate the tabbed magazine into the receiver well. A magazine catch engages a locking feature in a rib of the tabbed magazine so as to support the tabbed magazine in the receiver well. Once the tabbed magazine is empty, the tabbed magazine can be ejected by pressing a magazine release button without the need to rock the tabbed magazine out of the receiver well. The magazine release button can be configured to allow the user to eject the tabbed magazine by pressing the magazine release button on either side of the receiver. Once a loaded tabbed magazine is placed into the receiver well, the user can press a bolt stop button to release a bolt stop. The bolt stop button can be configured to allow the user to release the bolt stop by pressing the bolt stop button on either side of the receiver.