When the film was re-released in theaters after it became so successful, the Daffy Duck cartoon "Duck Dodgers in the 241/2th Century (1953)" was run preceding the feature at the request of George Lucas
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