I have a custom rifle on a 98 Mauser. The barrel Douglas and was their latest new steel in the day, middle 60s. The gunsmith who made it up was known for his bluing. When he blued this rifle the action was perfect and still is. The barrel came out pleasingly PLUM. He wanted to reblue but we just left it that way, it has character.
I have old Ruger Single-6 that has a wisp or two of purple on the frame. I have never herd WD causes purple. I think whoever started that one is full of brown.

I have some HAM Radio amplifiers where the Heat Sinks are Blued and have had the same thing happen. When checking with the manufacturer, they said it was not an uncommon occurrence. They told me that it was due to impurities in the steel. Of course for this application I don't case, though it would upset me if it happened to any of my Blued Smith firearms.

Bob

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Sag Harbor & Manhattan, N.Y.

Had an early flattop Ruger 357 with the bright Purple Blue Loading Gate.
MMC Rear Sight.
On my list of what was I thinking?

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NRA LIFE MEMBER

The NIB M57 I bought '67 ('S' prefix) had it's cylinder turn plum.
Rugers are noted for the color.
Rebluing those older cast steel framed SxS and single shot break open guns will often leave the frame purple.
Lots of Mausers, Springfields and Lee Enfields reblue OK but then can sometimes change over to plum with some time.
There's a mix of case hardened recv's there .
I did a restoration on a Ross 1910 Sporter that had been 'refinished'.
The receiver was a deep plum color from the hot salt reblue. The bbl was a deep blue color when I recv'd it.
Both had been heavily buffed and the bbl had not been taken off of the recv'r for the bluing process. So both parts recv'd the same polishing compound, prep, oil, cleaner, and tank bluing time.

No strict rules,,no simple answer it seems.
Some blame the investment casting process, but forged and machined parts seem to be effected as well.
Poor bluing salts, temp, time in tank, etc.

There are probably thousands of different steel types then add the different heat treatments they can be given.
It's a wonder anything matches coming out of the hot salt blue tank.

Winchester always had a problem matching color when using the Carbona Blue process as well.(Discontinued use in '38/'39 and switched over to DuLite hot salt bluing)
Especially on the Mod42 where the side plate was soft and the frame HT'd... and on the Mod21 where the frame is Ht'd very tough but the trigger plate which was made of the same alloy recv'd no HT'mt at all.

FWIW,,most parts that refuse to blue w/hot salt blue or turn unacceptable colors like this will generally blue just fine if done by Rust Bluing.
Slow Rust works the best on parts that give problems.

Thanks for giving the old thread new life!

At some points in time S&W revolver parts were blued separately in batches. Depending on the materials/ prep etc. variations such as "Plum blueing" were the result.

Not just S&W. There are Beretta semiautos that never left Europe (and never saw WD-40), with plum color slide stops and other small parts... Physics in Every Day Life... or Chemistry!

How about a 40 year old Leupold Vari X II in plum.

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LIVE FROM THE DAWGHOUSE

I can't tell you why, but I also have a 28-2 with a plum barrel. I've listened to a local S&W "expert" tell me several times that my barrel has been reblued while rolling his eyes, but I just continue to ignore him.

It seems to occur more often when some parts are heat-treated or processed differently than others, but I do not know enough about S&W to say this is the case here. The explanation of different parts being blued in batches seems just as valid.

Here is something else to add to the mix. Some cylinders are harder than others. I have made about 8 22 cylinders into 32 cylinders. I have ran into 3 that were considerably harder than the rest. The one in my shop right now if the hardest of the lot.

The heat treatment a steel has gone through will effect how it blues and retains its color. I have put parts in the same tank at the same time and they do not all respond the same, some take longer, some I actually take out and dip in water to cool off, then wipe with fine steel wool and put them back in solution trying get them to match.

Interesting old thread. I happen to like a nice "plum" on firearms; knowing it's not a harmful defect, I'm OK with it. This Detonics Combat Master I purchased a few years ago has a nice "plum" on the slide; common on the early Detonics.

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John

I'm baaack.
Great chemistry lesson by kenpofan.

Ask this question on an M1Garand forum and you will get further speculation. Lots of guys prefer the plum to black or grey park. Garands hare hard steel, some with lead dipped heals and most all were immersed in cosmoline. The thought is the cosmo does something to the park to make it plum. My 2 cents. And Luke I am your father!

Hey a good zombie thread...

Some of the Ruger guys find the plum guns collectable. Here is my Super Bearcat with a frame and hammer that turned plum (actually more of a brown):

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My sgntr is mor thn 30 chrctrs

Social pressure

My first 28-2 that I bought in 1978 had a slightly plum cylinder. The other one the pawnshop had was plum too. Neither were refinished. Mine was the slightly cheaper of the two, due to more holster wear. I couldn't really care less about it..