James Caan, Al Pacino and Burt Reynolds both turned down the role of Han Solo
Stormtroopers
The weapons the stormtroopers used were essentially the Sterling L2A3 9mm SMG (sub-machine gun) a military weapon developed in the late 1940s in the UK and adopted by the British and Canadian Armies in the 1950s. The curved left entry side mounted magazine was removed. And that was as much as it was modified for the film