It's entirely possible that a bullet fired inside this vessel wouldn't breach the hull, given the construction of Typhoon-class submarines in general. On the other hand, the interior walls and dividers can't protect all of the pipes, tubes, wires, and other conduits- and they're heading for the reactor now, so severing one of those is probably not a chance anyone wants to take.

Tsybenko shakes his head, but the Starshina looks curiously their way at the English words, so Tsybenko starts translating. "Yevgeny Andreiivich Matochkin," he says. "Comes from Chelyabinsk Oblast, in the Urals. I think from what used to be Ozyorsk, before they closed the town completely. Matochkin has been close advisor to President Antonov for years now on many policy matters, not only the military ones."