GI finishes NOS parts and refinished items

[byronroland]

I have 2 Carbines I am rebuilding/refinishing right now and I keep looking at the NOS parts I am getting from good reliable vendors. I am talking about triggers, slides, sears, mag release, safeties and any other item that goes on the gun.

When I look at the Parkerized finish on refurbished guns, receiver and barrels that are known ordinance refinished, there is a distinct nice green finish, a zinc phosphate with maybe a chromate bath. The finish almost looks like paint. I have a Winchester Garrand, 2 Winchester Carbines one Inland that all have this finish. The small parts I purchase still in the bag showing US GI purchase and pack are black with no phosphate crystal appearance? They look like black oxide.

Parkerize is a zinc phosphate finish. The finish actually grows on the surface of the metal, it does penetrate a little, but it actually changes the dimensions of the part, black oxide does not, it is a conversion of the surface. Parkerizing is a better finish and protects better, the grains or crystals provide pockets to hole oil and protect the steel. The black oxide is much thinner and provides much less oil holding ability.

In any event, the NOS parts all appear to have black oxide on them? There is no reason to black oxide a part that is intended to be Parkerized.

Are the NOS parts we run into Parkerized or black oxide finished. I am only talking about the GI stuff that can without a doubt identified as GI.

Yesterday I received a Carbine bolt tool to replace an aftermarket bolt tool. The aftermarket tool was OK but a devil to use. The US GI tool works correctly and is Parkerized, without question a green appearing phosphate finish. The aftermarket is black oxide.

Got a W trigger, US GI, today, nice black finish, no grain, no crystal appearance, definitely appears to be black oxide.

Any help would be greatly appreciated.

Thanks!

Information

Warning: This is a relatively older thread This discussion is older than 360 days. Some information contained in it may no longer be current.

[Chuckindenver]

not sure were you got that info but heres the facts..

parkerizing, is a brandname of a phosphate finish..
Black oxide is a commecial term for hot salts blue.
black oxide..is sodium hydroxide/amonium nitrate/ water. mixed and heated to 290 degrees, since AN is almost impossible for anyone to get, sodium ditrate is now used along with a secret mix..
2 types of hot bath salts are used, on for C class steel. and a second for stainless and cast steel.
phoshate.
the 2 most common types used today in the gun world..
manganese phoshate is dark grey, sometimes will appear black. used on most m1 carbines, Garands, and late 1903 Springfields.
Zinc phosphate light grey, in color and thicker in its coating, used originally on early Winchester Carbines, Garands, and US issue 100 rifles, and Remington 1903A3 and some late 03 Remingtons.
and used on all post war rebuilds, Garands, Carbines, ect.,,its light grey look is the give away.
phosphate, and black oxide are listed as a COATING and are a chem reaction to exposed metal surface, and they do not convert any of the metal surface, sodium hydroxide will etch the surface for the other chems to attach to the exposed metal, phoshate uses phosforic acid to etch the surface.
milspecs of the thickness of Manganese phosphate is 1-6 mils, Zinc is 1-9 mils of thickness.
milspec thickness of black oxide is .16 to 1 mil of thickness.
the original finish on {most} M1 carbines...
hammer, trigger, disconnect, spring guide, pins, bolt, extractor, firingpin, slide sping guide, slide stop latch, front sight pin, are black oxide{hotsalts blue..}
though some early hammers, pins and disconnects are natural steel finish.
the rest of the metal parts of the rifle should be manganese phosphate cept for Winchester, and that should be Zinc,
if someone who really knew what finish was what, and refinished a bolt, hammer ect...and sold it to you as original....you wouldnt know the difference. no disrespect intended,
example...if i had a nice original hammer that had little or no finish, and stripped it, and blued it,, it would look like a brand new hammer, even under magnification,,,you would be able to tell. {yes im that good} lol.

[byronroland]

Thanks! Exactly what I thought, the trigger, sear, hammers with a black finish are black oxide not phosphate. I could not find the crystal in the finish under a microscope, appeared as black ox as that is what it is!

And, what you are saying about the original parts being manganese phosphate and rebuilds being zinc phosphate is correct based on what I am seeing.

The only real issue I had was the black oxide parts being phosphated. When I go through Craig Riesch's book he lists Parkerize for a lot of parts I cannot find Parkerized and they are NOS.

Thanks! You cleared up a lot of my questions.

And, yes I do easily believe you can re blue and I could not tell the difference.

Byron

[byronroland]

When I review your post and the great information, then look at some of the NOS W Carbine parts I have, another question.

What about the slide? A Winchester M1 Carbine slide, is it expected to be black oxide or zinc phosphate? The ones I have appear to be black oxide?

[Chuckindenver]

im far from an expert on the M1 Carbine, though i do work on a bunch for refinish and restore.
what i have seen, is that 90% of the slides iv seen were Parkerized, and the slide stop detents are blued, its said that very early Inlands were blued all the way through.. though iv only seen some pictures, and not held a rifle that was blued.

[byronroland]

That follows what I have been seeing. Even the Winchester NOS slides are black oxide, one NOS Inland appeared to be manganese phosphate.

Appreciate your help.

[Chuckindenver]

dont confuse the black oxide with dark manganese phoshate.
black oxide is usaully brite. were phosphate will have a dull finish