I have one of the stand alone harbor freight cabinets and a Sears compressor. I use Brownells #270 glass beads for a very fine/silvery matte finish, very similar to S&W's factory bead blast finish. I have done some of my 3rd. Gen. S&Ws and my stainless Colt , ( carried on duty/gets scuffed up ) a couple times. I use about 60 psi and the finish comes out like new. If you are careful, once you do it a time or two, your results may impress you. I have owned guns from several well known custom gunsmiths and my efforts at this look as good as most of theirs, and better than some. I have tried other media, including Brownell's Fine aluminum oxide. This produces a darker, coarser, grayer finish that is probably more "Tactical" looking, but I don't especially care for it. I now use the Brownells #270/very fine glass beads almost exclusively for all of this kind of work.

As RobG5589 pointed out, you MUST completely disassemble the pistol and clean it, then clean it and clean it again before reassembling it. Make sure you get the media out of every nook and cranny. You definitely Do Not want any abrasive media left in your gun when you're done.

Years ago, I had a major, nationally known, "Professional" gunsmithing shop beadblast and blue a rather expensive,for the time, custom pistol. They left abrasive media inside that I did not discover until firing a couple magazines through it. The results were Not Pretty !!!

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NRA Life, COTEP 640