• It emulsifies in water, almost all other oils don't without a surfactant of some type.
  
• This means you can mix it with water and make very generous portions of it, and as Dave pointed out some call this Moose Milk, I literally have a bath of it.  When the water dries it leaves a film of oil, but you need a lot of oil left and it is slick and not something you want to put up in that condition.
• It also works as a secondary cleaner after you've cleaned with HOT water and soap (water is the "universal solvent" and the soap breaks up the oil).  If you dunk parts or spray them down with Moose Milk then you have an oily film on the surface and in some nooks and crannies you may not see. But I still would use another surface protectant, the Moose milk is your limited insurance policy in getting into areas you cannot easily get to.  If you had a tank of after-bluing oil dip it is basically the same thing. It holds water from the after blueing boil out and you can skim the milky partially emulsified mixture off of the surface the day after.  However I would be reticent to dip a firearm with BP fouling in a tank reserved for fine finished hot blued guns. But, if you had a dedicated one (the oils is not cheap).  I have used Diesel (dunked in a tank)  not for cleaning BP (but it works on other firearms), leaving a film, then wiped things down and used a better surface protector on the outside.
• If I don't have access to hot water, or soap and water I have cleaned with only Moose Milk and saved the better cleaning until the next time I shoot.  I would never do this at the end of the shooting season (if you slow down in the winter), I always strip and clean and thoroughly oil before putting them up for more than a month or two.
• It is not the best corrosion inhibitor, but you shouldn't use it as such except for limited time periods as Abilene pointed out.  I do the same thing, this gives me time to relax when I get home and clean in the next couple of days.
  
• This is a video from Todd's channel "Project Farm"  I like the way he does his test matrices and he is very consistent.  He rates it as a cleaner/protector.  His other videos are pretty good as well.
• I spray down the tubes of my shotgun at the end of the match and let them sit for ten minutes or more, then push a wad of paper towel through the bore and the melted plastic from my wads will push out like a snake skin.  I know one guy who is so lazy he sprays them, waits and then shoots smokeless loads through the shotgun to "blow" the plastic "skins" out.  I think I'll stick with a paper towel  and a big ole' 12ga Jag.
• In the summer when it is hot, I clean, spray down with Moose Milk, set the parts or complete weapons in the sun (the parts get HOT!), wipe them down and then use a rust preventative like EEZOX (or name your own poison here) as I reassemble everything.  For lubrication I have recently switched to my Mobil 1 Synthetic Grease and Mobil 1 Synthetic Oil lube mixture I use on everything else (not BP weapons) and even use the grease alone in the trigger area, I sort of fill it up.  So far no melted grease on my hands, but it is an experiment in progress.  I used to pretty much disassemble entire guns after a match, now I only do it about three times a year.   
• You don't have to worry about Ballistol soaking into and softening your wood like you have to be with conventional oil. And, Leather loves it 
• A tub of VERY hot water and lots of soap will do wonders for many things including incredibly fouled M240s, M249s, M60s, M2s, M242s, any sidearm, rifle/carbine, you name it.  I've watched guys spending hours trying to clean with CLP and then provide them with a wash tub full of scalding water, Mexican Soap (Lye) and fiber brushes and they come clean.   It's getting worse now...they want environmentally friendly cleaning materials.  Then there are the disposal forms and the environmental SOPs   

Major, I use it on wood and leather as well.  It will darken light colored leather.  I've used it for the oil finish on the last several grips I've refinished, and the grain really pops when it is still wet.

Tayhitman 

The 1866 receiver is BRASS.  It will stain whether shooting Smokeless or Black Powder or Subs.  I am also surprised Brasso didn't do the job. 

There are those of us who champion Brass rifles who actually prefer to allow the brass rifles to stain (patina??) and like the look.  All of my Brass rifles are well patina'd and I prefer that look.  It is however your rifle and it's your choice.

DO NOT USE SANDPAPER unless you use 2000 or 3000 grit wet/dry.  Any larger grit will actually leave scratches you may not be able to remove.