How do artisans correct warpage after CC hardening? Stuff happens even with exceptional care. What are common ways to realign parts after they are colored, in particular where close tolerances are concerned. Frames, side plates, any part that may have warped during the process. Looking for replies from real experience, not 'Well I would try this'. Thank you in advance.

I worked in Turnbulls shop in the early going and warpage was not supposed to be an issue.
But it did occur.

Some parts like lock lates could be straightened by simple lead hammer blows against a flat surface. Sometimes the warp was too severe and the part would show the correction as a wrinkle in the hard case itself where the part was bent back to position.

The glass hard case does not want to bend very far and going past it's limit will just end up breaking the hard surface case and it'll show.

If the case hardening isn't too deep, the soft core of the low carbon steel will remain and the part will still be usable as that will not be cracked as well,,just bent back to position as any soft piece of steel normally can be.

Some pieces that are thin, like trigger guard tangs and bows can get hardened deeply and of course the process 'cases' the part from all sides.
So a thin part with a deep case hardened surface from all directions can be extremely brittle as there isnt much of the soft core remaining.
Get one of those warped and try to bounch it back into shape can result in a conplete break. The now brittle metal being glass hard nearly all the way through has no 'give' to it.

Certain extra thin parts on some guns done all the time were watched for issued. One was the bottom plate of the Parker. At the front is a very thin thickness area and a place that would crack easily if polished too thin in a 'restoration to new' look and then case hardened thru.

Lever actions would close up their top rails where the bolt slides sometimes. I figured the placement of a slave bolt into the action while being fired would help reduce the occurance, but that was not to be.
Instead a set of crude steel wedges was used with a ball peen hammer to drive the action rails back apart the necessary amt to allow free movement of the breech bolt when reassembly came about.
The breech bolts were polished and blued.
Not every lever action closed up and needed surgery but it certainly was something we did.

Tangs on Sxs, Lever guns, Single Shots would warp at times and could usually be brought back in line with simple lead hammer blows.

SxS Top Levers would often warp downward so when assembled, the bottom of the end of the lever would be in contact with the top tang in operation. That places a scar across the top tang when operated.
Simple fix was to go ahead and assemble.
Then befor even moving the lever to the right, lift up on the back end of the top lever and shove a match book cover folded over or a business card the same betw the tang and underside of the lever.
Now with the Top Tang Lever boosted up in the air by the cardboard shim,,take a wooden or plastic mallet and wack the front end of the top -lever where it pivots in the frame.
That will drive the top lever down a small amt and in turn bend the back end up smoothly and evenly. Remove the card shims and the top lever will be nice and evenly spaced off of the top tang.
No drag or marks on either the top tang of stock.

Some SxS actions warped at the front of the action. The 'nose'/bbl pivot point being slightly warped downward making the bbls unable to be placed and locked back onto the frame.
Again not every one, nor a lot , but it did occur.
An arbor press was handy to set that straight again.

Adj were made to boost the colors and relax the actual hardening. This avoided some warping issues.

Much of the CCH craze was for the Colors anyway, not many were concerned about the actual hardening until metal galling started to be an issue with the soft parts.
Adjustments made again..

Then there were the oops jobs. The cracked actions, the modern steel alloy case hardened action and parts that came out like solid glass and just as brittle hard.
Things like that.
TIG welding fixed a lot, Case Color hid a lot.
Some things could never really be fixed right.
But most of it looked pretty.

Great post and informative. Please keep it coming. Input on modern steel would be helpful. Ruger, Browning, Miroku etc. These have been done, same process? These are vey hard steel to begin with.

I have had several single shot receivers and parts CCH'd by Turnbull. And two Ruger single action frames. They have developed a system by which they can process modern 4140 CM steel, make it case colored, and not have it brittle. Never had a problem with warpage; no dimension moved at all. And the others I had done were Sharps and rolling blocks. No problems there either.
4140 steel can't be case hardened by the traditntal methods; it already has enough carbon in it. They obviously have a special secret process for that.
I also have had it done by other places; one in Wyoming, and another I am trying to forget; a famous name, who turned a sharps lock place into a banana.
And yes, blocking and bracing is important as 2152 said.

Ruger steel is not very hard; 4140 does not need to be hard to function. That is why it is universally used for receivers, etc. It is the 4 points of carbon it contains that makes it unsuitable for traditional CCH methods; if you add carbon, then quench it, it will crack and worse. Go with Turnbull; he knows how to do it. I have no idea how; they must have perfected the process.
Also, the modern steel frames I sent him were not glass hard anyway; all we want is the color; the steel is already strong enough.
Now, if you have a wrought iron rolling block, that is different.

Thanks all for the information.

We were doing Ruger SA's, MArlin 336's, Ruger #1's and other Modern firearms frames back then (early 90').
We used the same pack (bone & wood charcoal, the same steel boxes, same furnaces, same quench (water pre-heated to 90*F).

Colors w/o any pretzel shape and hardening (too hard) issues is in the temp/time in furnace.
Very critical, a couple of degree's +/- was all that was allowed and by that I mean 2 degrees +/- IIRC.
Time in furnace was critical as well,,time to come out,,it was TIME to pull the box out.

Critical as well was how long it took from opening the furnace door,,removing the 'lid' and setting it aside. Then picking up the heavy box with parts inside out of the furnace and walking over to the quench and actually dumping it in.
It was all timed in a cadence of footsteps if you can understand that.
Not to slow as the parts/box would cool a slight amt.

The distance the parts fall from turned over box to the surface of the quench is also critical.
His process (at the time) used each individual part wired to the bottom of the box itself so when it fell into the quench, they never made it to the bottom.
But instead hung suspended in the quench a specific depth.
Then again after a few seconds,,a number count in your mind,,you pulled the 'pin' mounted on the outside of the box that all the wires were looped through. At that point all of the parts dropped to the bottom of the quench container.

Never reused any of the char, never reused any of the quench water. Never added any chemicals to the quench or pumped air bubbles through it, or swirled the water during quench time. Just the 90*F water.

Does it mean it has to be done this way?,,Absolutely not. Just like stock finishing, there are many different techniques and tweaks to produce the look.
This is what they came up with and had their best results.

Some modern steel actions regardless, did not respond to the process as others did.
Those 'bad actors' were simply put on the Will not Do list.

As already stated,, the name of the game was to get those Colors,,the hardening process was really never much of a concern other than to avoid it, the warping issues and chance of extreme/over hardening it could produce.

The market was sold on pretty colors.
Lots of re-done guns out there that are now considered 'original' even by the Exspurts.
We did hundreds and hundreds of them from Field grade to the rarest and Highest grade guns around. Lots of upgrades as well.

Very interesting to hear about how you processes CM steel. I thought it was some secret formula; rather than a secret process. I always wondered how it was done and not produce fragmentation grenades.
I also had some Marlins done, probably by you, that I forgot about.

Thank you 2152hq, very informative. Pretty well answers my questions.

Very informative.
Thank you for sharing that.

I attended the NRA Summer Gunsmithing class, at Tishomingo in 2004, to get some 'hands on" instruction for CCH. One of the main things I learned was to NOT get yourself into a situation where you were having to try to straighten a part that had warped. Build the 'blockage' and 'braces' needed to help keep the part as straight as possible. Going from "hot" to 90* quench there will always be 'some' deflection. Straightening can be/is an 'art', learned by trial and error, hopefully with guidance from an experienced person and a good dose of common sense (which isn't so common anymore). As I had ordered an oven from Paragon Industries I built 'crucibles' and handling tools, and a quench tank. I 'experimented' quite a bit after picking up the oven and getting it all set-up. My oven has nice and easy to use digital controls and has lasted without need of any repairs since 2004. I'd recommend Paragon whole heartedly to anyone looking for an oven. What else I learned was that 'new' low carbon steels seem to color 'better' than previously CCH parts. I tried as many different 'blends' of carbon rich materials to pack parts in as I could come up with. Wood charcoal, bone charcoal, bits of old leather (not modern tanned, as modern uses heavy metals in the tanning process) and 'blends' of those substances. I have settled on wood charcoal to pack parts that are being 'annealed' and bone for the colors. My oven is 230V electric, and when started and running it makes the meter go round and round at warp speed. It costs to use it. Most are concerned with colors, not the surface hardness that the process was originally intended for. Most have no clue of the processes involved, and even fewer are willing to pay for those processes to be put into practice. In my situation it is not economically feasible to CCH just 1 'part', and they'll ask for a discount if they have 2 to do. Some will want to do their own polishing, and the proper polish needs to be, before CCH, to obtain the best possible results. I will CCH for myself or a close friend, but I don't offer the service beyond that. I think I use that oven to heat treat tools I make for myself and sometimes a friend much more than I use it to CCH . I built a small 'library' of 'note book' info for my future reference. The articles from the 'Double Gun Journal', written by Oscar Gaddy, Brownells instruction, my notes and info handed out from the class and several other articles and references I found over the years. Good colors from CCH make a nice addition of 'bling' to a custom build. I never have had much interest in doing restoration work, Again, too hard to get paid for, for the work involved. In all, I am glad to be near the end of my working years, happier to be in the machine shop and completing some projects of my own in my gunsmith shop, than trying to straighten out some do-it-yourselfers "f" up.

We used only Wood charcoal and Bone Charcoal.
The Bone product was the same as anyone can (could at the time) buy from Ebonex in Mich(?).
Wood Charcoal came from a commercial source as well. Nothing secret in either.
Big bags of the stuff delivered by TractorTrailor.

The size of the material granules matters.
No 'dust' was allowed in the mix. That was wind swept away during the outdoor hand shovel mixing process.

No collections of worn out shoes and belts for leather to be charred, ground and used for 'pack'.

Only 2 mix ratios. 2:1 and 3:1
Wood to Bone char.

All the different Mfg'rs colors were adv as being able to be duplicated. But only 2 different mixes were used.
Any changes in pattern/color from there are very slight differences in the other variables of temp, time, etc.

Even the steel box that the parts were pack in for hardening was a shape that they spec'd out and kept duplicating. Two sizes were made and used. Each box was good for approx 25 firings IIRC. Then they got pitched.

Every part had to be carefully placed into the box in a well thought out position. It makes a big difference how they will be effected when they hit the quench. Warpage is a concern here and this critical placement helps reduce/elliminate it.
But all the other variables are in play as well.
The parts are packed into place with sufficient distance betwn them, the other parts and the walls of the box.
Nothing can touch and must have a min distance betw them of char packing.

No braces or blocks were attached to any parts to prevent warpage. A few were used in the very early going, but used less and less as time went forward. No Shields to hold Char close to the surfaces of the parts during the quench as in the Dr Gaddy methods.
All this just shows that there are many ways to produce the effect. So many variables in play. Hit on a collection of variables that works and you have found 'The Way'
No,,you have found 'A Way'.


The char is packed in very hard and dense. No loose areas or voids. Rocking and slamming those heavy steel 'pots' on a steel bench with the parts inside to settle & pack the char,,I can still hear it.

Many people did wish to do their own polishing. That was fine with the business.
You got back what you brought/sent it.

Polishing was extra over the cost of the CCH process.
All previously CaseHardened parts/frames that were being prepared in Shop were drawn back/annealed before any work was done.
One reason was that w/o doing this the new CC would often not look like what you would expect. Dull colors and sometimes the colors were not much to look at. A slight mix of grey&blue. Not every one, but it was a good chance of it and you don't want to do things twice anyway.

The other reason for annealing was for polishing and engraving recutting.
Polishing thru a hard cased surface is difficult as compared to a soft steel surface.
Plus trying to re-cut engraving thru case hardening is very difficult (yes I know all about Carbide bits, I reserved those for Win21's).
Re-cutting existing engraving w/o annealing leaves the work looking like trash.

Yes, the bone charcoal from Ebonex, don't remember where I sourced the wood charcoal. Agree, packed tightly, tap tap tap until it will settle no more. Never let the part touch the inside of the crucible, or parts touch each other in the crucible, orientation of the part can matter. Placed a small piece of brown paper on top of the 'pack', before placing the lid on sealed with clay, to burn off any residual O2. Most times the paper would have singed edges, but didn't completely burn (no O2 to support combustion). If the paper burned to ash, or some of the charcoal turned to ash , you didn't have it packed tight enough. Never tried 'shields', to hold the charcoal closer to the part during quench, some did during the class. Always annealed before polish, then cased. Did some quenched in aerated water some without. I haven't CCH everything, side plates, old Savage 99 levers. a few Mauser 98s, a few shotgun receivers (old single shots and SxS that were originally CCH. A Rem Rolling Block or 2. I guess I kinda lost interest when every Tom, Dick and Harry decided they knew more about it, but had never done it themselves,,,, and all their info came from UTube and the web. In a 'working' gunsmith shop you can get a lot of; "I haven't got the tools to do it myself", from some that come through the door. Takes more than having 'the tools'.

Fascinating read. Thanks for taking the time to detail the process. Sounds like a long learning curve.

Anothers' experience; https://uppermotradingco.com/hepburn.html He made a 'paste' of charcoal briquets, sprayed his cast "Hepburn" receiver with WD40, packed it in that "paste", and 'cooked' the crucible in his wood stove. Claimed excellent result, hard surface with great color.

quote:

Originally posted by fjrdoc:
Fascinating read. Thanks for taking the time to detail the process. Sounds like a long learning curve.

Yes, "long learning curve", as not much reliable written information seems to exist. It has been said that when Colt brought back the Model P they had to run an extensive R&D for CCH the frames, as those who had previously done the work had retired/passed and took their "secrets" with them.

There is a very detailed article in Double Gun Journal; I have it here somewhere; anyway, the problem was how to process 4140 steel and not make it brittle. It does not need any "case", nor any more carbon. That is the process which Turnbull (2152) developed. To my knowledge no one else can process 4140, but there might be. That is truly sorcery.
I did read that Colt forgot how to do it but they were not using CM steel.

quote:

I attended the NRA Summer Gunsmithing class, at Tishomingo in 2004, to get some 'hands on" instruction for CCH

I attended the same CCH class at Tishomingo too. I would have to look up the date but about the same time frame. John Hackley was our instructor. We spent a lot of time machining "bridges" to help support critical areas and prevent warpage. I have quite a few good pics from there including the quench at night. Spectacular light show from the pieces of carbon. One photo was with the receiver still in the crucible right before the quench. You can see the receiver through the crucible. We got varied results. A little over half of the parts gave spectacular colors, deep blues with gray accents. The rest was not so good. Some of them we did over. I had a pre 64 Model 94 Winchester that turned out spectacular. A large Martini action that was just as good. A Stevens Favorite, not so good. I don't remember anyone with serious warpage. Right before we packed the parts in the crucible Hackley had us clean the parts with Simple Green and not clean it off. He also recomended the a piece of brown paper added to the top of the mix to consume any oxygen. We sealed the lid with clay. We used roughly 50/50 bone and wood charcol.

quote:

Originally posted by Craftsman:

quote:

I attended the NRA Summer Gunsmithing class, at Tishomingo in 2004, to get some 'hands on" instruction for CCH

I attended the same CCH class at Tishomingo too. I would have to look up the date but about the same time frame. John Hackley was our instructor.

Joe Beck taught the class in 2004.

I've straightened color cased floorplates that bowed a bit in color case.

I used a simple setup in a 6 inch Kurt machining vise.
I glued leather to 3, 1.0 inch diameter pieces of round stock.
The round stock with leather is placed so two support and one does the bending.
A dial indicator is used to track the amount of bend taking place and to find the yield point to where it will stay straight.
Technique: apply pressure, watch the indicator needle, back off, apply a little more, back off, apply a little more.
basically just work it in the vise with the round stock until I get it where it needs to be to fit right.
The leather covering on the round stock eliminates marring of the surfaces.
bending parts back to straight is a bit of a art as I see it.
I straightened a G33/40 receiver that someone used as a club this way, it was badly bent at the thumb cut, I got it perfectly straight it shoots very well, personal rifle.
I straightened an 08 Brazilian receiver after heat treat the same way, warpage caused by re-case hardening, it's the only one I ever had that totally freaked at re-case hardening, too expensive to scrap it, had to make it work and did and it works perfectly.
For whatever its worth those are my experiences in straightening parts.
I imagine I would address a side plate or similar the same way.

Thank you everyone for your contributions. Great place with unselfish artisans willing to share their knowledge.

You can get color (on low carbon steel) when only heating to 1285F, or so. Have to get to 1333F or above for surface hardness. The higher the temp (when quenched), the harder the surface hardness. But also, a bigger chance for warping. Depth of 'case' depends upon how long ya' 'cook' it.