Where is the best place to get aluminum oxide media,and should I use the 100 or the 120.
Either will work just fine. Graingers should have it. Some TSC locations have it also, but in 80 grit. Garnett will also work just fine.
Graingers only sells it as a 50 lbs bag for $84.
I've been using Harbor Freight's 220 grit and while it works, it takes for-freaking-ever. Going to try my pop's 70 grit tonight with a little lower pressure.
Brownells is sold out of 120 grit right now too.
I was told to search Abrasives in Yellow pages and got zilch but maybe your area will fair better.
Have not tried Garnett.