Abstract: A cartridge catching system designed to attach to picatinny rail of a firearm to receive spent cartridge cases from the ejection port of firearm is provided. The cartridge catching system has a container body which is downwardly angled to deflect the spent cartridge cases towards the bottom of the container body. A connecting rod where one end of the connecting rod is fixed on picatinny rail of the firearm and other end is placed within an elongated hole is provided on a rod receiving assembly. The rod receiving assembly is mountable on top or within the container body to optimize the position of the container body depending on the type and size of firearm. A spring actuated ball is provided inside the elongated hole on the rod receiving assembly to fit onto the semicircular hole of the connecting rode to provide an easy ON/OFF mechanism for attaching/removing the cartridge catching system making it easy to empty the container body.