One of the slowest side objectives to complete. Here's how you can do it faster.
Method 1: Press 'E' repeatedly to pick and drop the artillery shell while walking to the objective. If you rotate your helldiver while picking up and dropping the shell you can build up more momentum than usual when using this method.
Method 2: Press 'E' then '1' to toss the shell in the direction you're walking. What you're doing is picking up the shell then switching to your primary before the shell gets to a fixed position in your hands. The upward momentum of picking up the shell launches it far in front of you. Reminder - you have to be walking forward beforehand to launch the shell far distances.
DISCLAIMER: Don't toss the shell if you're too close to the artillery because you'll get it stuck on the top and you cannot get the shell down (I lost a mini-nuke that way)
Also it works while you're crouched