I have never had much luck with Cold Bluing, however I've never blued an entire gun, just did touch-ups or individual parts. The bluing wears off fairly easily (at least where hand contact is made) and I am using what I deem the best of what's available which is Brownell's Oxpho Blue paste and / or Birchwood Casey Bluing Paste.
I have tried all the tricks such as heating the gun up prior to bluing, using multiple coats, cleaning the surface with alcohol before heating, etc. - still the results for me have been lack luster.
If I had a gun with a bad finish that I really really liked, shot a bunch and wanted to keep it forever, I would have it professionally hot blued - but that's just me. Yes, cold bluing at home is cheap - but IMHO you get what you pay for with bluing. Some guys report descent results so maybe they have a better technique than I do.
If your M10 is a seldom shot revolver, then the Cold Bluing may be enough to "float your boat".