Okay, so we have always used Sieze by force for firefights, but I suppose...
When two guys are shooting at each other with shotguns, that's not a move. They just take 3-harm both.
If the players want do to anything else than that, it's probably a move, that modifies this outcome. (Acting under fire to, for instance get out of the way and avoid harm altogether, sieze by force to sieze something, which might modify harm, go aggro to modify the other part's behaviour)
Anecdote:
We had a situation when the battlebabe started going aggro in the middle of a fight, and I was like, "Dude, you can't do that, roll sieze by force instead". Of course, instead of going aggro, he could just, you know, shoot them. Which would correspond to getting a 10+ on Going aggro, and them forcing his hand. So we didn't actually need to bitch about whether he could use his best move or not.
Have I gotten it right?
Or, are two guys shooting at each other always Acting under fire, if no other move applies?