The off board artillery markers are Heroics & Ross 1:300 guns, painted gloss red (they are markers) on BF plastic bases. HR guns are ridiculously cheap so are just the job. It makes life so much easier having counters at the edge of the table (showing orientation) than having them marked on roster sheets (which no one here ever wants to use after hard day at the office). Keep it simple, keep it visual. We use markers for everything around here:
Retreating (shell burst) and very commonly used, because we play Piquet, unloaded markers (crater).

Casualties are marked with clutches of stones on 'terrained' pennies, suppression markers are tufts / small bushes on 'terrained' pennies. At some point I'm going to break up some plastic kits for bits of wreckage for other markers.