Something I just want to run up the flag pole here for 9th but...you can't weave gunfire as some of us thought and just checking if I was the only one missing this.
To Quote: "...then if any other weapons with the same characteristics profile are also being shot at that unit, resolve those attacks before resolving any attacks against the target unit with a weapon that has a different characteristic profile"
So this would mean that if you were to run a devastator squad with 4 lascannons and 6 boltguns and were hoping to bait out the storm shield dude from a squad for bolter fire, you cannot. All 4 lascannons must go first then all the boltguns.
Naturally, if you bring various different weapons then you can but since the common optimal loadout is often 4 of the same (or just all the same in a unit) this could be a note worthy thing to keep track of.
Ofcourse doesn't stop you using a lascannon from a different unit to then lead for the other squad but it isn't possible to alternate guns within one unit alone unless they bring some sort of higherlander set-up of guns.