Looks like glass bead to me, as well. That one looks fine. Personally, I like a bit finer grit better. You can get a finer finish with smaller media, or lower air pressure, or both together.
Recently bought a 15-3 that is not all original: Replacement grips and mediocre refinish on the cylinder. Has a few areas of minor pitting, barrel has plum bluing which may have been a factory finish.
Gun is a great shooter and extremely accurate. Since I plan to keep it forever, I would like it to look as great as it shoots. Local gunsmith with excellent reputation will bead blast and hot blue for $220 total.
Anyone done this? Pics? Suggestions? (Besides just shoot it.)