Heat/Nitre bluing small parts

[Dixie Gunsmithing]

Jim, that is what I was taught. Some old double receivers had problems anyhow, like the Ithaca Flues, and flame coloring one of those is asking for trouble. They were bad to crack where the water table meets the breech lobes on either side. They had a radius in that corner, but they still cracked. I've seen several of those "flame colored" Flues show up on auction, and I would not tip one with a ten foot pole.

Several gun designs could be affected over that, and some parts, as it is according to how they're made, and how any heat treating or coloring is done to them. Of course, screws, pins, etc, it seems not to hurt, as the spring range of tempering softens ones pretty good, yet still leaves them with some hardness. Most small pins were made of spring wire stock anyhow.

 

[45 Dragoon]

Dakota,
If the screws/screw pins are new, heat them to cherry red and quench in oil (I use used motor oil, some use water). Now, they have been hardened. Descale the screw/screw pin with 320 sandpaper (you can use steel wool on the pin, you don't need to polish it. This is a good time to "clean up" used screws/screw pins.
After descaling, you can polish with compound or give a "brushed" look with the same 320 paper with the screw/SP chucked in a drill motor. A few cloth patches under the paper will allow the paper to contour to the screws/sp's head without "flat spoting" it.
Now you can reheat the screw/screw pin to the desired color. When approaching the color ranges, control the heat and quench when the desired color appears. Practice. If you go past the color range, you will have to Descale again. If you go past the Light blue (last of the colors) go ahead and re- harden the part , descale and refinish, and color again.
With 13-15 screws/ screw pins per open top, it takes time. The best thing though is better wear resistance and increased lubricity.

Mike
www.goonsgunworks.com
Follow me on Instagram @ goonsgunworks

 

[Gunplummer]

James, you are wrong about that.

 

[Dixie Gunsmithing]

I think it is according to what one considers cast iron. Below is an article on Gray Iron.

http://steel.keytometals.com/articles/art115.htm

The type of iron used in older Shotgun receivers was case hardened. I could not tell you what those were actually made of. Probably another low carbon iron.

Below is an article from ASM on it:

http://www.asminternational.org/documents/10192/1912175/htp00302p027.pdf/9e5abf6c-46fe-4a08-9f71-2d6cc59cf311/HTP00302P027

Here is another from Chymist:

http://www.chymist.com/Heat%20treatment%20of%20iron.pdf

 

[James K]

"James, you are wrong about that."

OK. I wonder why gun companies waste a lot of money making things out of steel when they could just use the much cheaper iron.

Jim

 

[Gunplummer]

Probably because of the same reason that buildings and bridges went to steel. Steel is a lot stronger and stretches more. Read the section on Tempering and Hardening.

 

[guncrank]

Yes you can get nitere salts that hot with a camp stove.
I use a cast iron skittet and a small stew pot.

I ran into a problem with getting parts to soft as the temp is anneualing range.

There is a gunsmith in FL that use it to blue revolvers and he says that there is no problem with heat treatment. I have seen some of the guns and they are pretty.

 

[Alex Johnson]

Older shotgun receivers were made of low carbon steel and case-hardened to increase the surface carbon content so they could be surface hardened. I think that cast iron which does have extremely high carbon content was sometimes used for gun parts during the mid 1800s because it was easy to cast, something that technology at that time did not allow in general for steel parts. I have seen pocket pistols such as Manhattan arms where the frames showed evidence of being cast. In these instances I suspect the cast parts were put through a separate heat treating operation designed to decarburize the parts to remove the excess carbon and render the part more ductile. Afterwords they would have been case hardened to provide a wear redistant surface and often the decorative colors we like so much. I highy doubt cast iron was used to any great deal into the cartridge era. Most of the dhotgun receivers would have been shaped initially by forging operations and subsequent machine and hand fitting.

 

[Bill DeShivs]

Alex- apparently you haven't examined very many single shot shotgun frames!

 

[Alex Johnson]

I guess I was referring to double guns, but I would be leery of shooting any of them with a cast iron frame. Ballard made some of their actions out of cast iron I have learned and they had horrible reputations for durability. In any event like I mentioned earlier I suspect that even these were treated to convert the material to a more malleable condition.