Arsenal page 33 describes a Safe Target System that prevents friendly fire. This would be a useful gadget, if friendly fire had any kind of feasibility. As rules are, it's doesn't. The only chance of hitting a friendly target is by rolling a critical glitch in an appropriate situation, which is seldom enough that nobody ever thinks twice about shooting into a not all hostile crowd or especially into a melee combat situation.
I have always been unhappy with how rules handle firing into melee combat, but when someone recently decided to fire a wide burst into a melee fight to negate the target's partial cover (which was the shooter's team mate that the target was fighting with), with little to no chance of hitting anyone but the target, I decided enough is enough. Our table has two melee specialists (my character when I'm not GMing is one of them, so maybe I'm biased), so such situations are not uncommon. I'm considering suggesting the following house rules next session, please tell me what you think.
Stray Bullets House Rules
Bullets fired using SS, SA and narrow burst modes miss their target and become stray bullets if the attacker has no net hits in the attack. When using wide burst mode, the number of stray bullets is equal to (number of bullets fired) – (half of attacker's net hits, rounded up).
Stray bullets create a transient cone of suppressive fire ranging 1 meter around the original target and up to 10 meters behind it. Other characters within the suppressed area at the time of the attack must defend against a threshold equal to the current number of stray bullets with a Reaction + Edge Test (+ Dodge if on full defense). They defend one at a time, starting with the character with least Edge (or when equal Edge values, GM's discretion). The usual defense modifiers apply. If the test fails, the character is hit by one bullet, suffering damage at the weapon's base DV (base DV +1 on a glitch, base DV +3 on a critical glitch). For every hit, reduce the number of stray bullets by 1 for the next character's Reaction + Edge Test until all bullets or all characters are accounted for.
Note that characters may be surprised by the attack, e.g. friendly characters may not be expecting an attack from that direction. Apply appropriate Perception and Surprise Tests at GM's discretion. Surprised characters defend with Edge only.