I'd be more worried about a 3 minute set-up time prior to a single and round-ending spray of fire (if it's a game-ending spray, then no one would ever play it).
Think about noobs trying the game. They'd stand there, "What do I do?" Experienced players scream back "BUILD!", and they go "...". It would be horrible to attempt to create an audience for such a game.
You need some kind of catch or excitement that would be easy for first time players to grasp on to. Otherwise, noobs and experienced players alike will leave out of frustration, and it would be unlikely that the game would ever get played much.