Some of the stuff you guys worry about is baffling. Millions of barrels have been blued on the inside over the years. Any hot dip commercial blued barrels are blued in and out. You talk of plugging the bores. Anyone who does this is risking the plugs blowing out when the barrels reach temperature in the molten salts and expelling hot bluing salts all over the place. This is not recommended.

Rust bluing done properly eliminates bluing in the bore. If you are worried about it then get all your barrels rust blued. I've paid good money several times for rust bluing from reputable people and places and had the bores rusted much worse than any hot dip bluing would ever cause. I don't send them any more business.

Deadeye Bly wrote on Apr 18^th, 2015 at 9:27pm:


Saw a fellow grab the jar of vinegar real fast when the plugs blew out of the ends of the barrel while in the hot tank and spattered him pretty heavily with hot salts. He only did it once, and it only took once for him to learn that lesson.
What amazed me was the amount of crap that hot bluing will break loose from a heavily fouled bore. When comparing the before condition with the after hot bluing results in an old barrel he ran through the hot tank, you'ld almost swear the barrel had "grown" deeper fresher rifling.

And yet, as anyone that uses taps knows,  black oxided examples are touted as being more lubricious . Black oxide would be considered a form of hot bluing would it not ??
The coating helps to keep metal chips from sticking on a tap,so would it not also help prevent leading ?? Apparently not.

There are a couple of things I've noted that were not touched on. The OP stated a CM (CrMoly) barrel. Depending on the bluing process used CrMoly barrels frequently have to be pickled to remove the "impurities" from the surface of the steel or the bluing will exhibit an undesirable warm tone or worse yet plum spots. This is not an issue with cheap hot salts bluing but certainly is when using some of the rust bluing solutions.

Pickling of course is the process of boiling steel in a dilute acid to prepare the surface of the steel for further processing. Obviously this lightly etches the surface of the steel.

Further, Yes agreed millions of barrels are indeed hot salt blued inside and out. Then folks who compete send them to people like me to diligently lap and polish away the resulting etching that promotes copper streaking that can throw the POI in a single shot.

Using a vented plug when bluing a barrel is not new. The practice has been around almost as long as browning has. Anyone who would immerse an unvented barrel in Hot Salts is either foolhardy or simply doesn't know what their doing.

I'll offer this as well from a great deal of experience. Even when a barrel is diligently prepared, well coated in anti corrosive grease, plugged with good maple plugs one of which being vented, after 10-15 turns through various boiling solutions there is always a coating of black soot on the inside of the barrel. Where is this black sooty crap coming from? I can only assume the repeated boiling and cooling is forcing some matter out of the pores of the steel.
From previous experience of prepping high end Anschutz and FWB used in 10m competitions I know that a barrel performs best when these micro pores and scratches are finely filled by repeated use and polish sessions. I back this up with having seen the micrography that was done on samples.

So adding all this together. Any barrel after bluing will likely have cleaner than desirable pores. And will benefit from a systematic conditioning routine. However one would be advised to avoid anything that increased the amount of etching/porosity on the bore surface as that will only further promote accuracy robbing fouling. Metal fouling is what I'm referring to

I've rust blued a good number of barrels and have never had a rust problem with the bore, at least none that I can detect.  I don't plug the bore either.  I use a piece of cold rolled rod grooved on the ends to hang the barrel in the damp box and in the boiling tank. After I degrease the barrel I give the bore a good swabbing with car wax and when I remove the barrel from the boil I immediately wipe the bore with two dry patches followed by a patch with car wax.  The patches will sometimes come out rusty looking but that is from deposits in the tank.

JS

It really depends on the metal I'm working with and what colour is correct for the gun I'm working on.

My go to bluing is definitely Radocy. It is a mercuric chloride based rust bluing that is spot on for english, belgian and Italian guns. It is also the only product I have found that will blue a post 64 winchester mystery metal receiver.    (You need to Login or Register to view media files and links)

I also use Pilkingtons. More of a charcoal black, less flashy

Herters is a good formula but not as good as the Radocy

Laurel Mountain Browne is excellent for that era. You need to completely ignore the instructions to get a really hard lustrous finish.

If all else fails I fume with nitric and sulfuric. Again not as liquid blue as the belgium formulas more of a deep black.

The pic shows an 1880 buckhorn done in Radocy sitting atop a barrel finished in Laurel Mountain that has been carded and scratched very very heavily. Its a good contrast to highlight the differences

Great information guys, Thanks!

Bob