US Patent 9188399 Receiver catch

A catch is used to secure upper and lower receiver portions of a modern sporting rifle to one another. The catch may be mounted in either receiver portion and includes a shaft on which a body is mounted. The body has a hook and a cam follower positioned on opposite sides of the shaft. The cam follower engages a cam surface, which rotates the hook into engagement with a contact surface to secure the receiver portions to one another when they are pivoted into a closed configuration.