Cheating

[low_bidder]

Imp, Op fire requires a moral check that is influenced by lots of things, most of which I don't remember. That is why you get what you call a ripple effect. I see it mostly with infantry. IIRC, initial hit % is one of the checks for op fire. So a unit that didn't pass the first time might the next because another unit fired and it had a better shot at that second unit.
That is why I use the 't' key to target an opponents unit even though I'm not planing on fire at it that impulse. Not sure if it matters, but it seems to , which matters to me.
I have started setting the overwatch range of my A0 unit to 40 or so and that appears to have cured my Op fire problems. Of course I only have two games going now and my opponents are not very co-operative with my research efforts.