Tamiya's only have light, medium and heavy, the DBC I think also has/had a 'super light' setting? (one hit, one second reload).

Another idea for the electonics wizz's:
Have a series of small emitters placed at various points - doesn't need to be anything bigger than a 9V battery and enough circuitry to fire the appropriate pulsed signal at a random interval every few minutes (or maybe they fire once?). Each team gets to place / aim into spots of their choice to prevent camping.
Couple that up to a flash bulb and maybe a smoke pellet to complete the effect of simulated artillery.