OK, if I have 4 monsters in a room, lets say bugbears, with 2 of them behind a turned up table for cover. When the PCs get to the door, these monsters are already ducked down behind the table. What I want to do is, on their initiative the 2 behind the table jump up and fire their crossbows, then duck back behind the table. Is this doable in one round? Minor action to pop up, standard to fire, move to duck down. Or is that too much?