In the 1940s, Joseph Caine notice that the bolt action Lee-Enfield .303 proved ineffective and they were often out gunned by invading forces using semi-auto rifles. In the 1950s, Joseph Caine designed the first prototype of the M5 rifle, the T5E1 rifle. It featured a undetachable magazine and it can fit 10 rounds. On later models, the magazine was removed and only hold 5 rounds. The magazine cause the problems of the rifle and often jammed in test trials. In the end, Cascara Army and Navy rejected the M5 rifle and adapted the 5.56mm M16a1 rifle. It was never exported to other countries outside of Cascara.