Critical hits with spirit barrage

I am trying to figure out how critical hits are applied when using spirit barrage. I watch very closely for critical hit indications and I am just not seeing them very often when using spirit barrage. I currently have a 54% chance to hit. I would appreciate some tips on how it is applied with spirit barrage.

As I understand it, each attack from spirit barrage has its own chance to critical hit (using yours), the aggregate then applied on explosion/culmination, but that last effect cannot crit (or else it would double dip).