It does lead to a question about morale checks, which I think can be best illustrated by a scenario.
6 goblins corner a dwarven pistolier with 4 loaded wheel-lock pistols. The dwarf wins initiative and shoots a goblin. It falls, he cleaves and shoots a second goblin. The same thing happens, and he drops a third goblin, cleaves one more time and drops a fourth goblin, but now is out of pistols and cannot attack again.
How many morale checks do the two survivors take? Because goblins have a -1 morale, gunfire triggers a morale check, and the multiple shots and multiple deaths allow multiple scenarios. I can see a few possibilities:
1. The goblins make morale checks after each shot, plus a check at the end of the round at -2 due to having more than half their group killed in one round.
2. The goblins make morale checks after each shot, with the two at -2 due to the shots killing a target and half the group being dead.
3. The goblins make one morale check at the end of the round at -2.
4. (this one extrapolates from the rules) The goblins make one morale check at the end of the round at -4 because there are three situations forcing a check (firearm discharge, death, and half dead).
5. (the roll, roll, roll your die method) There are tons of morale checks - one for each shot and one for each death.
6. (my favored one, with totally no rule support) The goblins make a morale check immediately upon the first shot being fired. They make a second check at -2 immediately upon the first death, and a third check at -4 once half the group has been killed. The rolls occur only when the morale penalty gets worse, so if the dwarf had fired, killed a goblin, shot again, and didn't kill that target, there would be morale check #1 for the gunshot and check #2 for the death, but no check for the second shot, because it doesn't cause a further morale drop.