Which one is best

[Bentong]

for cold blue application? Van's instant Gun Blue >> http://www.vansgunblue.com/ or Birchwood Perma Blue >> http://www.birchwoodcasey.com/sport/blueing_index.asp?categoryID=1&subcat=5#11

I'm planning on doing a crosman barrel

[howie1a]

I use Brownells bluing and I find if you heat the barrel a little it opens the pores of the steel and does a better job, and also use scotch bright fine grade to apply the bluing with this is what works for me. Howie

[RedFeather]

Oxypho seems to be the best of the cold blues.  It comes in a paste or liquid.  Haven't used the paste but been told it is the better of the two.

[SDale]

Red and Howie are right. Oxpho Blue is the best cold blueing I've ever used.

I did a write-up that's in the library section. It's for Birchwood Casey's Perma Blue.

There's a little twist with Oxpho Blue though. It works better if it's scrubbed in using 0000 Steel Wool, fresh from the bag. The oil in the steel wool seems to help yield a deeper, more even finish.

[Jaymo]

Brownell's Oxpho Blue. I use the paste. Other cold blues can be spotted and smelled from a mile away. Oxpho Blue can't. It actually does a good job of bluing. I've blued the hammer, trigger, etc of a Dan Wesson revolver with it and it's indistinguishable from a good hot blue.
Homemade hot bluing isn't difficult. go to       http://www.homegunsmith.com and join for free. Then scroll down to "gun and stock finishes". Click on that. Then click on "Hot blue my way, step by step". It's pinned at the very top.
Hot bluing is definitely an outdoor project, but it's not all that hard or expensive.

Of course, you could always do some home Parkerizing.

[Jaymo]

Of course, there's always Brownell's spray/bake on teflon/moly finish, or Lauer Duracoat.