I had a Para Ordnance pistol done in Black T several years ago and can't say enough good about the finish. Slicker'n snot on a door knob, extremely durable, optically pleasing. Regretably, the Para turned out to be a piece of ka-ka. Thus, the gun, and the finish along with it, went bye-bye.
Caution: The finish does take up some tolerances so, if you are going to have any gunsmithing done, have the finishing done FIRST.