doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Case Coloring

good: you may add chemical processing to metallurgy in the list of industrial procedures of which you know little.

Accidental fatalities from the industrial use of cyanides are diminishingly rare. In 40 years of handing and transporting and the stuff in quantities from microgrammes to hundreds of tons I never saw or heard of one.

Mr. Molloy, for making that statement above, I think a lot of us would love to buy you a pint (beer, not cyanide!) should you ever visit the U.S.

Not to be a bore, but within the plating industry, cyanide poisoning is a real risk.
Note to self: Should you be visiting a plater regarding the recoat of your Chrysler Imperial bumpers, and smell violets, skeedaddle.

I read you Mr. Molloy, but for whatever the reason, the reality is that he charges $260 for bone charcoal pack and $270 for cyanide.

http://www.ronsgunshop.com/pricing.html

Go figure, eh?

SRH

Chuck;
thanks for posting the tempering scale.
KyJon;
To now answer your question, this scale pretty well sums up my thoughts. You will note the highest tempering temp this scale went ot is 1,000�F which produces a hardness of about 31Rc. To twmper at 1200�F or above is going to drop that hardness well down into the Rc 20s. This is simply not a good use of 4140. 4140 is a great steel, but if I had a gun frame made of it I would want it given a proper heat treat & blued, just forget the color. If one wants color then use a grade of low carbon steel & case harden it. This gives the advantage of that "Glass Hard" skin which is wear resistant. You will definitely feel a difference in working a dropping block action or closing a double which cocks the ejectors by pushing them in as they rub down the breech face, between that hard case & a part in the Rc 20's. 8620 is a more modern alloy which I understand has a much higher strength than the old standard 1018 etc.

I agree with 2-p that there is little reason to use a plain low carbon steel alloy (like 1018 - 99.82% iron and 0.18% carbon and th th th th that all, folks, nuttin' else in there) for a modern gun action. There are modern alloys that are better and can still be case hardened. If, however, you are a traditionalist, you can use 1018 with confidence. The case hardened low carbon steel receiver has withstood the test of time for sporting arms.

DDA

I'm curious as a lab in a chicken kitchen about the steps, temps and resultant core hardness that Doug Turnbull and Brad Bachelder get on the Parker Repro when they charcoal colorcaseharden.

So 2-piper is it possible to color and not harden with a cyanide process and is it at a temperature low enough to not soften the metal (4140) too much? And I agree that with 4140 I would rather have a blue receiver. But some insist that case color is a must. Personally I find most cyanide colors to be too brash.

Jon;
I don't really know that much about what all can be done with the Cyanide process. To harden though requires the part be above its critical temperature prior to quenching. Even presuming that Cyanide can be used to produce color below this critical temp, it would still I suspect require a temp much higher than I would want to submit a gun of mine to, whether a low carbon or higher carbon alloy steel. Either way you are going to end up with that soft surface.

I think a good question would be how soft is too soft. Rifle barrels of 4140 for high pressure cartridges are typically listed as having a rockwell C hardness in the mid twenties. It may not even be possible to treat 4140 to be much softer than that.