[scJazz]

The MOBHack guide located in the Mobhack folder is very useful for exploring things like this. I was about to answer but Jud already did. Still quoting the guide...

Fire Control - This affects accuracy, especially against moving targets. Values over 99 are fire control radars, with 101 being better than 100. Field changes colour if AAA radar is issued. AAA radar is only worthwhile for AA units, obviously - SP SAM, AA guns, SP AA guns. SEAD aircraft seek out units with active AAA radar - there is no EMCON in SP. Anti-radar missiles may destroy the radar, if not the firer. (As a reference point, 5 was used as a maximum in WW2 data - e.g. king Tiger )

Range Finder - This makes hitting targets easier, especially for firers who did not move. 20 is the level for laser range finders, use 6 for the ranging coaxial rifle calibre MG as used in UK tanks, or 8 for a ranging .50 MG as used in Chieftains. Use around 6 to 10 for optical range finders as in the M48/M60/Leo 1. values under 5 tend to be used for WW2 type tank sights. For reference - 4 was generally the max value in SP 1 (e.g. panthers) barring some specials (e.g. 8 for the Nashorn, which used a stereo optical range finder of artillery observer type).

Stabiliser - this allows the unit to move and still keep a fire control solution (target lock) on its current target (if any) - and reduces the effects of own firer movement. Larger is better. Units with high FC and RF can engage slow moving helos with AP shot. (Almost anyone in range can shoot at hovering helos).