Modeling Multiple Shots for Skilled and Unskilled Combatants in a Science Fiction Setting

Skill using the logo, even though I will
likely change it.

Wow. That is a wordy title for a simple idea: "How are combat skills applied?" 

In this game, we have established that a target has a defense of 2-12 and an attacker must match this number on 1, 2, or 3 six sided dice. 

Technology in a science fiction game permits a character a ridiculous amount of attacks with a weapon. In a 10 second combat round, someone with a six shooter can shoot six times, no matter their ability or skill. Without any applicable skill, that person gets one shot with 2 six-side dice and 5 shots with only one die. They are shooting fairly indicrimatly, they aimed with the first shot then switched to random blasts. Without any skill, the aimed shot MUST come first subsequently followed by random shots. This is the penalty of not having a skill. 

When a person has a skill, they are entitled to more aimed shots at a rate of one attack per level of skill. When attacking one target once, they get to roll all 3d6. However, if they attack more than once or at more than one target, they may only use 2d6 per attack. Skilled persons may mix aimed and indiscriminate fire in the same round at will.  

For example, a marine with 3 ranks of skill is guarding 2 hatches with a 6 shooter. He sees 3 robot drones approaching from his front and engages them. He rolls 2d6 for the first attack. Then rolls 2d6 for the second. Before he can shoot at the third drone, the hatch on his right opens and he indiscriminately fires a shot at the person opening the door. He rolls a single 1d6. The hatch slams closed. 

He still has 3 bullets and one aimed shot, so he returns to shooting at the drones. He aims with the first shot using 2d6. Since he has 2 more bullets, he fires them indiscriminately at the robot drones for two more attacks made with a single die each. 

In the image, shots are numbered in order.
Red is for aimed shots and green is for indiscriminate.  

This combat does not describe damage resolution as it would occur in the game. It is merely an example of a single person shooting. In later examples, we will see that this marine would have plenty of time to reload and/or move.