You won't get gear them every time, if you get the event missions finished you can farm them and fire each cannon 1 time every hour. That's a lot of gear, but i prefer to keep them for the 4th. That's when you get gear more often.
@@ver3982 Just farming them in general to fire cannons and get free gear/lures. But this is how to get the cannon balls for the mission. I finished all these missions in 2020 lockdown.