Since the Corrupted are some illicit part of society per se, why would they need to “smuggle” anything?
Smuggling suggests bypassing some legitimate government blockade, but there is nothing of that sort between the SoulWardens and the Corrupted in the Great Cleave.
It would only sort of make sense if they mean “smuggle” as in “hide”, but why would you hide ammunition? And in a fort you control? Because you expect to lose the fort and then retake it again and use the ammuntiion?