So when someone wants to scrap a drive, you want to aim the shotgun at the center hub of the brown disks from far enough away that most of your pattern is contained within the 4" diameter of the brown disks. Don't worry about the head mechanism, drive electronics. Center the pattern on the disks.

Use #4 shot and you'll destroy the disks for certain. If your disks are like mine, you'll be picking up parts in a bucket for 25' downrange of where you had the disk stood up on a fencepost when you shot it.

Or you could just hammer it with a sledge until you mash up the brown disk platters, your choice. Your job is to destroy the brown disk platters.