The [Bren gun 7.62 x 51 mm] bullet to his chest was stopped by a silver cigarette case given to him by his brother.
Nah..! Not even three or four such cases stacked up would do that.
But kudos to him, all the same.
Maybe they meant a (9mm) Sten gun?
Silver is pretty maleable, plus it probably had cigs in it as well!...............