Black Airsoft BB's are the best from all reports, and they worked well for me. Size I use is .25 gram not sure it matters if they are that size or the .20 gram size. It doesn't take much in a plastic bowl to do the job. Maybe a layer two or three BB's deep. Cool Whip bowl will work but something with a screw or tight snap lid in #5 plastic is better. Cool whip works but tends to leak around the lid. White BB's are reported to not work well.
Walmart, Meijers, Amazon, most of the big sporting good chains.
You can order from this guy on the forum if you have any doubts or difficulty
http://castboolits.gunloads.com/show...raying-bullets Smoke4320 sells the BB's and you can purchase a 1 pound sample pack of 3 or maybe 4 colors to try. More expensive than the harbor freight red but in a whole different legume in terms of quality and ease of application.