yeah
closest we have right now is the Megashark, it has one barrel (unlike the Minishark and Chain Gun which are visibly miniguns, and the SDMG, which would conceivably also have one barrel, but in-game the bullets just fly out of the dolphin's nose) and it also fires fast enough that it could be comparable to a modern rifle (relatively speaking, of course — the "golden standard" AK47 fires at ~600 rounds per min based on a quick google search, i'd assume that would be fast enough to make your bullets blend together into one line in-game)