According to statistics kept by the NYPD between 1854 to 1979, 240 officers were killed in gunfights. Of those, 229, or 95.4%, were killed within 15 feet of the shooter, and 85.4% were within 6 feet. According to the FBI, nationally, between 1991 and 2000 50% of police officers killed were within 5 feet of their assailant, and 71% were within 10 feet. Most police - and civilian - gunfights are at very short range. This includes rural incidents as well as urban.
From the same source, the average hit percentage of NYPD cops from 1990 to 2000 varied between 10 and 20 percent. Remember, typical range is less than 15 feet. Also, as the Rate of Fire and magazine size of a weapon increases, hit probability decreases. The difference is noticible even between a revolver and a semi-automatic pistol, let alone with automatic fire.
The more military the combat, the lower the hit rate, even though soldiers are generally much better shots than policemen, and use much more accurate weapons. It's estimated that 50,000 rounds were expended in Vietnam for every (estimated) enemy dead. Now, that probably counts everything from target practice to sniping, but even giving generous allowances for this, that's a lot of shots.
So, clash, you ask, what's that got to do with the price of beans? If every shot were accounted for, the probability of a hit would be so low and combats would take so long that it'd be an excercize in futility, and boring as all hell. So in the StarCluster System, I abstracted all those probable misses fired off into a single (double with mastery) check with a decent chance of actually hitting once a minute. From my research, most firefights are over within 4-5 minutes. By making each round a minute, and allowing for long term tactics- even if abstract - a StarCluster firefight is usually over in 4-5 rounds. Like real life, there are far more wounded and incapacitated than dead in the end, like real life, you move around a lot and use cover, and like real life it's all over fast.
So abstraction can make things seem more real. Who'd a thunk it?