Real Deal Case Colors

[Bruce Day]

The way they were made.


Now I'm no expert, but I have wondered why we usually see color differences between the trigger plate and frame on internal hammer guns and the sideplates and frame on external hammer guns. So I have asked around and the responses from people who do case colors is that the frame must remain soft(er) than the plates in order to withstand firing shocks, so they are treated differently during the case hardening process. As a result, the plates retain color longer when exposed to wear.

Bruce Day, Parker beginner and aspiring neophite

[B. Dudley]

Wouldn't the parts be all assembled during the CCH process?

[Bruce Day]

No. Not at all. Each type of part is packed into the case hardening crucible separately. What I have learned is that the crucibles containing the various parts are not subjected to the same furnance time.

[Bill Murphy]

Deleted. I asked the same question and got my answer. Thanks.

[edgarspencer]

Originally Posted by Bruce Day

What I have learned is that the crucibles containing the various parts are not subjected to the same furnance time.

Are you certain of that? I received regular orders from Colt, in West Hartford for these "crucible". In the case of Colt, they were a 5x5x10" box, cast in a martensitic alloy (called CA6-NM, for those that care) I have been in the heat treating department at Colts many times, and, at least in their case, the boxes aren't unclamped until back to room temperature.

[Dean Romig]

The parts were strategically placed in the crucibles with bone, shards of hide and various other biologic 'packing' around the parts. The frame was not placed in the crucibles as an assembled unit.

[edgarspencer]

After my last post, I decided Bruce is right, in that the parts, after the normalizing cycle at 1650-1700 degrees, get a temper/stress relieving cycle, at under 1125 degrees, in a controlled atmosphere furnace, and not in the boxes they are normalized in.
Dean is correct. They are individually heat treated. The secret to the color is in the packing, and composition of carbon bearing packing material.
I never hear anyone mention it today, but one of the old materials was horse manure. No $hit !

[Dean Romig]

Most any carbon bearing material can produce the desired results.

My neice, an aspiring artist, fired this pretty piece of pottery packed predominantly in salt-marsh straw. So here we have a new twist on color heat treating.





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[ed good]

edger: your temperatures regarding hardening and tempering are most interesting and specific. are they specific to colt's process only?

[ed good]

bruce: your comments regarding the differences in how frames and trigger plates are processed is interesting and new to me. perhaps all parts are hardened to the same spec, but then tempered to different specs, depending on the amount of elasticity desired?

i am no expert either, but do find the subject of factory shotgun receiver hardening and coloring to be fascinating.