Home made sandblast cabinets..lets see them

What I buy is called "Black Beauty" like the horse :-D but any black slag media should work. I live in the boonies so I have to drive to a masonry place -- gotta drive for EVERYTHING lol -- but I think Tractor Supply sells it. Be careful not to buy anything coarser than fine though or it can tear up your metal.

It sounds like your air pressure setting is adequate (I'm guessing you have a regulator) but you may need to adjust it up or down depending on the metal and what you're trying to remove.