I've used BC Superblue and PermaBlue, but after refinishing an SB2 H&R receiver with Brownell's Oxpho Blue Creme, I'll never use the BC stuff again, the Oxpho Blue is good stuff, not hot blue quality, but for a cold blue and as easy as it is to use, I recommend it highly. See Handirifle's "Cold Blue questions" topic in the Gunsmithing forum.
Tim