What kind of 12 gauge shells do I need?

[OnceWasAnOptimist]

There is a store near me where I can buy 12 gauge shells but they don't have slugs. They do have a limited variety of buckshot and birdshot but obviously I'm not gonna use birdshot. What type of buckshot do I need to ensure I can destroy most of my head? What do I look for to determine which is the most powerful? If they don't have anything powerful enough I can also just buy metal slugs online and while I'd rather use a slug, buying online might lead to detection. I'm going out into the woods so traumatizing other people isn't a concern but I don't want to have any chance of consciously and bleeding out after shooting myself. Also I can't find info on shotgun acquisition in MN that isn't conflicting so if anyone knows how long the background checks take and whether I can actually get a normal pump action same day after passing background check I'd appreciate it. CTB document

 

[Temporary Breakway]

anything #4 bird shot and higher will work, but you generally want to go as overkill as possible with what you choose
Choose something that will paint your brains several yards away, such as 3" nitro 000 buck
Remember, even 7 1/2 birdshot will likely work, but the more overkill you go the more guaranteed it is, such as exotic slugs for home defense for psychopaths, or specialty made slugs like the hornady set sabot
Anywhere on the head, nose level and up, is likely to be instantly lethal as well, so dont worry about angles or how deep beyond basics like:
Do not aim directly under your chin
Do not aim right into this back of your throat
Aim to the Brain, or brainstem
Remember, you have less than 5% of a chance to fail, and that assumes you fuck it up in an obvious way