A gentleman selling older rifles at a recent gun show told me that the metal finish on early Springfield's including Krags was basically a coating from oil in the quenching process that wore away fairly quickly.  In other works, there was no chemical reaction as with various bluing processes.  He said the mottled black appearance so common in older firearms was simply remaining areas of this coating.  I have a rebarrelled Model 1896 with a really nice even finish all over.  Per this gentleman, virtually any rifle looking like mine has been blued in some timeframe after it was originally made.  Is this correct?

'bote' - The original finish on U.S. Krag receivers was Case-Hardened. (There was more to it than simply 'oil quenching' - complicated heating in ovens packed in bone or leather).

Barrels were 'browned' (blued) and this was done before assembly to case-hardened receiver.

U.S. Arsenal Refinishing instructions used at Manila Ordnance Depot in 1907 indicate: receivers were lightly polished, barrels were brushed (to remove surface rust), the bore was protected with cosmoline and sealed with wood plugs (at both ends).

The barreled-receiver was subjected to processes of: boiling lime water, caustic soda solution, browning (bluing) solution, steam chest, and carding.

There will be a difference between the finish on U.S. Krags that are 'original' armory finish and Krags that were reconditioned.

The surface colors of case-hardening do seem fragile and easily worn.

A homogeneous color on receiver and barrel suggest refinish to me.

Probably the bigger issue is who did the refinish? Armory or Aftermarket.

Thanks, Butlersrangers!.  I was aware that the receivers and some other parts were case hardened but quenched in oil rather than water.  The color variations in the common case hardened steel is due to intentional uneven quenching.  The different colors represent steels of different crystalline structures.  I was always under the impression that the color from oil quenched case hardened steel was a uniform outer layer of steel of a particular crystalline structure that had a gray-black color.  But I was told recently that the dark, uniform color was due to the burnt or coked oil.  The coating theory seems feasible as a uniform layer of steel from the quenching would be thicker and more durable.

Initial Springfield Armory finish as explained in May 20th, 1899, "Scientific American". Note - The receivers and barrels were not assembled, when they received their respective finishes.

(The Refinishing process, as described in 1907, had the receiver lightly polished to remove corrosion and then it was 'browned' in conjunction with the attached barrel. IMHO - It is likely the now polished case-hardened receiver would react to the 'browning' process a bit differently than the barrel steel).

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Let Larry Potterfield, from Midway, show you how its done...

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I often thought about sending a beat-up old Krag to Turnbull Restoration and letting them have their way with it.  They do beautiful work and the color-case-hardening is IMHO outstanding!

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BEWARE when monkeying with case hardened parts!  As the name implies the hardness is only so deep... so when you start sanding and filing dents/imperfections you maybe removing the case hardening.

Case-Colors are rather fragile and vulnerable to wear and abrasives. Here are some non-Krag examples that have survived a 100 years.

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Here is about as good as it will survive on a U.S. Krag:

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The "browning" they describe is called "rust bluing" today.  It is the process of converting red iron rust (Fe₂O₃ to black iron oxide - Magnetite (Fe₃O₄)

It is actually pretty easy to do at home, and with a little practice, you can repair small spots on a larger piece without disturbing the original finish. 

It is far less hazardous than modern hot caustic bluing, and is far more durable.

The color from both color case hardening and nitre (fire) bluing is very delicate.  The only way I know to reliably protect it is to either not touch it, or to cover it in some sort of varnish.

I've attached a few pictures:
Picture 1:  Czech Vz52 rifle parts that I rust blued.
Picture 2:  Chilean Mauser screw that I nitre blued.
Picture 3:  Colors possible with nitre bluing.

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OOOOOOO, nice pretty colors on the butt plate!  :o  I'm going to have to try that!

Rust bluing is by far my favorite.  I think it imparts a rich, dark, deep blue and, I agree, is the more durable finish.

Cold bluing gets laughed at but you still can get good results.  I use it a lot on small parts and touch-ups.

Plum Brown works great for getting something to look old with a nice even, kinda mottled brown patina. Like an old musket barrel or socket bayonet.  Actually, I get confused sometimes because the word browning is also used to describe the brown finish applied to really old firearms. 

Plum brown works well. So does Laurel Mountain Forge. I've refinished several old .22 rifles and one Marlin 336 using this process.

Just to reiterate what 'AFJuvat' and I have said, the "browning" process, in Springfield Armory references, was rust bluing. (Also, the color and appearance are quite different than hot caustic bluing and other modern finishes).

Of course, what we now refer to as "browning" has been utilized on firearms, since they were invented.

The odds of me ever owning a Krag with the original finish intact is dependent on me winning the lottery.  I am an optimist, however, and want to be prepared.  Before I spend my lottery winnings, I want to be able to distinguish the original finish from blueing.

P.S. Stephen Lester of Turnbull recently told me they don't do any Krag work. 

This thread made me think of something else:

I see a lot of old guns with buggered screws, some of which can be hard to replace. I've not seen it discussed on any forums, but an old machinist showed me a trick which can work wonders. You have to choose your projects, of course. Some should be left alone, and some are too far gone, but there is a broad middle ground which will benifit from the work.

Grasp the screw in a vise, between blocks of wood. Get a small ball-peen hammer with a smooth face and start tapping at an angle on the screw head, bumping the metal back into place. You also need (to renew the slot, which will frequently close up from the tapping) needle files, a sharp fine hacksaw blade, and perhaps a Dremel. Polish with emery cloth before refinishing. No two cases are identical, and the fix may not be "perfect" but it can often produce a huge improvement, on a middle-grade gun.

Practice your technique on a few worthless screws before you tackle something important. The key is the tapping, to return the slot as close as possible to its' former shape - just polishing off the burrs (as is sometimes encountered) doesn't do the job.

Dick - Thanks for the buggered screw restoration hint.

Here are some Springfield Armory (Hill Shops) photographs from the early 1900s, showing work going on in the 'hardening room'.

Some of the photos appear to show 1903 Springfield bolts being processed for hardening. I don't know the order of the pictures, but, there are furnaces, vats for quenching, iron boxes for parts going into the furnaces, and wooden shipping boxes destined to go back to the Water Shops, (where the forged parts came from).

Quite the shop tour, if we can figure the sequence. There had to be a lot of continuity of methods from 'Trap-Door', to 'Krag', to '1903'. Beautiful Arms came out of dingy work places.

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Great pictures. Thanks.

I agree!  It's fascinating to see how manufacturing was done over a hundred years ago.  I've been in plants built before WWII, and the design of the building alone is amazing to me.  Sometimes, I wish more pictures like this were documented... going all the way back to pre-Civil War era!

YouTube has some fascinating videos on the huge stationary Victorian era steam engines, and their elaborate houses, which are still operating today. It is not clear whether they are connected to anything, or just run "for show", but I'd bet at least some are still actually performing a service.

Neat pictures!  Thanks for posting.

The quality of this thread would seem to dictate being made a sticky,,,,,,,,,, 8-)