The red shirts would go down. Storm troopers can hit people, they are only forced to miss Main Characters. This leaves room for Obi-Wan's sage comment: "Only Imperial troops fire with such accuracy."
You see, the jawas weren't main characters...
Alternatively, the red shirts kill all of the stormtroopers without suffering a scratch, then die to a hundred different inane causes. Red shirts are permitted to be effective - they just have to die sooner or later.
Ah, Fushi Ryu, your law-of-inverse-ninjas-esque version bears much explanatory power. This is why the lone stormtrooper in the battle of Endor is able to shoot Leia, but when there was a whole battallion of them she was safe.
On the other hand, a lone red shirt is in just as much trouble as a horde of them.