So basically, focus fire set to false seems to allow squads to re-roll misses into hits... just not on the squad it's targeting but on other squads.
Basically it seems like:
- focus fire = True means that misses can not hit other squads;
- focus fire = False means that misses can hit other squads, allowing the squad to deal some additional DPS to other squads nearby.
It doesn't seem to affect DPS versus the targeted squad, but it's hard to tell.
Here's 4 tests. In all tests I only targeted the squad in front.
Test #1, Kar 98K rifles. Rifles have no focus fire option, and misses do not deal damage to the second squad.
Test #2, FG 42s. Focus Fire = False. Misses deal damage to the second squad.
Test #3, PGrens STG 44s. Focus Fire = False. Misses deal damage to the second squad.
Test #4, FG 42s with Focus Fire set to True. Misses now do not deal damage to the second squad.