I got some a few months ago to play with. It looks about like AA#9 gunpowder, I.E. pretty small. I really didn't like what it did for guns. It won't cut like silicon carbide and won't make a shiny finish like glass beads. I think it would be great for removing paint without doing much to the texture of the metal, like your friend would want to do but I don't have much use for it on guns. What it IS really good for is filling benchrest sandbags. It's pretty heavy and really fills out the bags well.
Something I have been wanting to get is the newer ceramic media. Supposedly it lasts a really long time since it doesn't break like glass beads, just gets smaller and still cuts. A knifemaker friend told me about it, and swears by the stuff. Someday I'll get some and give it a try.
Another blasting tip for new folks - don't ever use aluminum oxide to prep for parkerizing. It contaminates the surface and you can't get a decent finish after using it. Use only silicon carbide.
