Bluing

What you are looking for is "blanket bluing"
Find the dirtiest old motor oil you can, a piece of wool felt, and a torch.
The carbon in the motor oil is what you are after in the dirty oil. The wool must be pure wool and no synthetics.
Heat the gun part to the point where the oil soaked felt when applied to the metal burns nicely and slides across the surface. If it sticks, it is too cold. Too hot, well, too hot and you can tell because it slips to easily.
The metal will just start to take on a slight blue ting when it is the right temp for this application.
Heat the metal slowly and evenly. NEVER get it hot enough to glow.
Once you have done the whole thing, polish with medium steel wool dipped and kept wet with the dirty warm oil Once you have done this then you can inspect and touch it up as needed.
Practice on several pieces of steel pipe
This procedure will give you a very deep and black finish. It is a very old method from who know when but was used when I was in the army (a long time ago). It was never done factory, just field.
It actually gives the metal a porous coating that holds the oil.
 
The Stratton book on the No4/No5 states that oil blackening was accomplished by heating the metal red hot (740 deg C), dipping it in oil, letting the oil drain off and then wiping off any burned on carbon. He also states that the 1950s production LB rifles were given a fairly high polish before this process.

Barrels and receivers would have been heat treated prior to finishing. I am not a mettalurgist, but there is a heat point where excessive temp would anneal (soften) the metal requiring that it be re-heat treated. I do not see this as a good idea for DYI refinishing of barrels/receivers as it is very difficult to gauge the temp of the metal. You can "blue" small parts by heating them to a cherry color and then immersing them in a can of oil.

I am a big advocate of a parkerized finish for military weapons. Parkerizing solution operates at a fairly low temp (180-200 deg F), so there is no possibility of affecting the original heat treatment. It is a simple process. Longbranch did employ parkerizing for some original late war production and overhauls.

Virtually all of my parkerizing, except for barrels and outsize pieces, like Garand op rods, gets done in a large, oblong shaped ceramic crock pot and it works great. I can parkerize every part of a Garand, less barrels and op rods, this way.
 
purple said:
The Stratton book on the No4/No5 states that oil blackening was accomplished by heating the metal red hot (740 deg C), dipping it in oil, letting the oil drain off and then wiping off any burned on carbon. He also states that the 1950s production LB rifles were given a fairly high polish before this process.

Barrels and receivers would have been heat treated prior to finishing. I am not a mettalurgist, but there is a heat point where excessive temp would anneal (soften) the metal requiring that it be re-heat treated. I do not see this as a good idea for DYI refinishing of barrels/receivers as it is very difficult to gauge the temp of the metal. You can "blue" small parts by heating them to a cherry color and then immersing them in a can of oil.

I am a big advocate of a parkerized finish for military weapons. Parkerizing solution operates at a fairly low temp (180-200 deg F), so there is no possibility of affecting the original heat treatment. It is a simple process. Longbranch did employ parkerizing for some original late war production and overhauls.

Virtually all of my parkerizing, except for barrels and outsize pieces, like Garand op rods, gets done in a large, oblong shaped ceramic crock pot and it works great. I can parkerize every part of a Garand, less barrels and op rods, this way.
Click to expand...
*NOTE: I work in a metal heat treating industry, and have been researching the methods of blueing used by Winchester/S&W/Colt for several years for myself.*

Stratton is full of misinformation. The described "oil blackening" was obsolete for a production plant before WWI.

Two comments:

1. DO NOT TRY THIS AT HOME!

I would strongly recommend against "Oil blackening" for a number of reasons.
First would be that the described method is far too high a temperature, and you are missing several steps. In fact it is DANGEROUS without specialized knowledge of the steel alloys involved and their specific properties.

You have now destroyed (removed) ALL of the existing heat treating of the receiver.

The oil "dip" has quenched your receiver, now the receiver is brittle. Look up "low number Springfields" for a description of what the result might be.

Missing steps:

Then you have to "draw" the quench by heating it to a lower temperature (probably between 200-600*F~ alloy and service dependent~) and letting it cool slowly.

The locking area's are spot hardened (likely through induction).

We don't know any of the temperatures involved, and they are dependent on construction material alloys, and desired outcomes.

Any time you heat treat judging temperature by colour, the temperature is very subjective. The ambiant lighting, time of day, how long you've been awake (fresh eyes), and metal alloy all have a role to play. The primary judging criteria is almost entirely based on previous experience handed down from the journeyman to apprentise over a several year period. We don't have this luxury today.

2. Parkerizing (Phosphating) did not begin at Long Branch until midway thru 1950. The confusion with "new war-time" guns being Phosphated is because Long Branch did not mark their FTRs on the British pattern by using "FTR" and a date.

Inglis was a different factory, and used Phosphating during the war on High Powers and Brens.
 
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