Why does the barrel on the ROCs protrude from the slide? Seems like that just exposes the rifling to possible damage. Also, what is the point of crowing a barrel? Seems like that would serve to protect the rifling.
It protrudes from the slide because it looks bitchin'. Crowning the barrel, properly done, assures that the gases leaving the barrel with the bullet do not kick the bullet off axis, causing unstable flight. When the crowning is done correctly (which it rarely is), shooting cast lead bullets will produce a characteristic, symmetrical "lube star" on the crown surface:
