Case hardening.

[Mike Hunter]

Since I’ve been doing CCH here in the shop for the past 15 or so years, here are some notes and thoughts on Color Case Hardening:

1. It’s been brought up before, most original CCH is 80-100+ years old…which make it pretty hard to compare, colors fade/change.

2. I suspect that the surviving number of firearms with 80-100% factory CCH is in the 1-2% range, so very few examples to judge from.

3. Firearm companies, back in the day, did true Case Hardening, quenching at temperatures most restorers will never get close to. Back then there was an “acceptable” failure rate… I.e.. Warped or cracked frames. Somewhere in my notes I have that number for Winchester, and it was north of 10%. After 1903 Winchester stopped CCH frames because the failure rate was deemed too high. Restorers today don’t truly Case Harden the frame, unlike the large manufacturing companies, we have to have 0% failure rate, temperatures and processes are changed to reflect this.

4. Manufacturers also had the luxury of “virgin” receivers with soft steel. Restorers are working with metal that has been case hardened previously (some multiple times), has been in service for 100 + years, and oftentimes has had repairs (welds etc.). A good restorative color case hardener has to keep all of this in mind.

Not too long ago, I had an 1886 come into the shop, the owner recently had it recased (would not tell me by who). He snapped the butt plate trying to install it on the stock, and the frame was so warped that there was no way it could be reassembled. Looking at the steel, I could easily tell that it had been quenched at too high of a temperature, and more than likely into a brine quench solution (which cools quicker that water). I had to anneal the frame, then spend a couple of hours straightening the frame, make several blocks to keep the frame from moving, then a second annealing to get the frame to take the proper ”set”. Final CCH with the frame all blocked up so that it wouldn’t move, and follow up with a proper tempering.

Lots of thing to consider when judging Colors.