- Edited
It seems to me that general hits on the opponent with a primary fire / all primary fires done * 100 would be the most sensible solution. Alternatively (if it's not a problem) a separate acc for secondary firing - that is: (general hits at the opponent with a shock balls + all hits with bursts shock balls) / all fired shock balls * 100.
I guess the sum of accuracy from both types of shots (primary + secondary fire) will not make sense. These two values conflict with each other. Some players only shoot shock balls and kill a lot of enemies while others mostly use primary fire.