I've received the answer; there is no downside to the bolt action rifle.
The game don't track the ammunition or rates of fire so the bolt action rifle is better than a assault rifle, for the rules.
But, according to the answer, the concept of the game is a narrative wargame. You can win with a full bolt action rifles army but you miss the point, you miss what this rules have been created for. Share an experience where the two players have fun.
With this point of view, I understand better this game.
But for a more competitive game, 2 AP for fire the bolt action rifle can be a solution.