Finnish "plum" barrels

[Calfed]

I've got two Finnish MN's that have barrels with a reddish "plum" color to them
A "B" barrel M39



And a Finn 91/30



What is the gouge on the plum coloring? Any idea on what causes it?

Thanks

Information

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[Patrick Chadwick]

As far as I am aware, there are two possibilities:

1) If the finish is dull, then it is probably just ordinary "bluing" turning into rust. Dealers like to dignify this slow degeneration by describing it as "plum finish".

2) If the finish is bright, then it is probably the result of an alloy material (nickel, maybe) in the steel that does not quite harmonize with a bluing process that had been set up for a different steel.

- could, of course, be a bit of both.

From here on, I think you need someone with better knowledge of metallurgy!

Patrick

[Calfed]

Thanks, Patrick

These barrels both have a bright plum coloring. I'm familiar with the plum or "brown" coloring that bluing turns into as it rusts. This is different.

I've heard that a high nickel content can affect the bluing process and render different coloring. Another possibility that has been raised on another forum is that the bluing process is sensitive to a certain heat range...get out of this range and the coloirng can be affected. I'm not sure which is correct, or if either is correct.

[jmoore]

I've seen that finish on other similar Finns. I thought it was the original finish. It may have been "blue" to start and quickly turned color- it wouldnt be the only time it's happened. Ruger had a run of M77 rifles that did the same. Also the WWII Beretta pistols that have the pink slides!

[onlycrimson]

Look at SVT 40's. Almost all of them have plum bolt carriers. Something with the arsenal reblueing did it, not sure what exactly.

[Phil McGrath]

Also when the barrels were blued the tank temp could have been on the high side.

[RCS2]

Check if they have a "B" on the barrel that means probably barrels from Belgium thus the plum color. I have a FIMM M 39 like that.

Check in http://www.762.54r.net

[jmoore]

Check if they have a "B" on the barrel that means probably barrels from Belgium thus the plum color. I have a FIMM M 39 like that.

Check in http://www.762.54r.net

I've a couple of "B" barreled Finn variations, but they are regular old blue color, IIRC. Non-serif'ed "B" and a script "B" too.

[Buntlineguy]

When hot bluing low temperature or not enough time in the tank will come out plum color. Harder steel takes longer to darken in the tank.
B