Rather than get a simple +1 dmg for firing three bullets at someone I thought it would be more realistic if each bullet were determined seperately...
The player rolls as many dice as they are firing bullets. They allocate the dice results as they see fit. A modifier of -4 is applied to the second bullet, -6 to the third, -8 to the fourth and -10 to the rest. The effects of a dodge are applied to ALL bullets.
Eg: a player fires three bullets at an opponent, they roll 12, 16 and 9. Their goal was 13.
For the first bullet they assign result 12, target is 13, so it hits, 4 successes.
For the second bullet they assign 9, target is 13-4=9, a critical hit (if you allow them), 3 or 6 successes.
For the fourth bullet they assign 16, target is 13-6=7, a miss.
The target rolls 4 successes on their dodge so only bullet one would hit unless you allow critical rolls.
With regard to critical rolls, I am of the opinion they should be ignored, simply inflicting normal damage.
This system also allows you to determine the number of hits against a shield as well.
For full autofire I suggest a straight penalty of -6, roll dice equal to bullets, spread hits over targets in the area affected. Normally a 2 meter area is covered, each extra meter might cause an extra -2 to goal.
Suppression fire can be used by firing a number of bullets over a specified area, bullets divided evenly. Anyone enetering each meter area is attacked at the appropriate goal. Bullets that didnt hit remain to attack the next person entering the area, but get a further -2 modifier to goal for each successive target. Rolls of 19 or 20 cause the bullet to vanish.