This is a general GM'ing problem for me, but it feels more acute when I MC Apocalypse World.

How do I pass time in the fictional universe without making my players feel as if I take important time from them where they can act on their motivations?

 In my experience the action is always ongoing, with no situation where I could skip hours or days of in-game time.

Are there any custom rules you use if a PC chooses to wield, for example, a handgun(2 harm) in each hand? Should we just use the one weapons base harm and not fret about it?

I was thinking could it be a custom move each time they use the guns:
When using gun akimbo style roll+cool(hard maybe?).
On a 10+, you do +1 harm. Add area tag to the guns for this use.
On 7-9 you do +1 harm.
On a miss, you spray-and-pray, doing -1(maybe-2) harm.

Please let me know your thoughts on dual wielding and the custom move.