Storage Containers for Grenade Quest

[Maximvs]

I've looked in every storage container on PR, Tortuga, and PDF.

I'm afraid you need to read the clue a tad closer in your Journal... there is only one location you can get the items from...

The Box Containers and Barrels must be retrieved from Kingshead.... no easy way around it. If you have never done the Quest (you'll have to do it twice - first for 10 boxes and 10 barrels - then back to kingshead again for 20 boxes and 20 barrels - then finally you can do Padres Fort for the last 10 barrels and it will say 'any fort' in your journal - and PDF just has 10 exactly) it is best to take a good healer or 'frontman' (soneone who knows their way - and will hit targets first while you do your searching).