doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com CC of Modern Guns?

I do not have the credentials Marc does, but worked for 35 yrs as a machinist & was around a considerable amount of heat treating & took a short course on it during my apprenticeship. Case hardening is for use on low carbon steel, through hardening is used on higher carbon steel. The characteristics of the outer case can only be accheived by leaving the case in a hard condition, ie drawn at a very low temp. This low a draw on a high alloy steel is quite apt to leave it in a brittle condition. "ANY SMITH" who would case-harden a modern action with higher alloy steels I would not allow to even make me a firing pin, as they have no regard for safety. You may well be confusing artificial chemical coloring for true case-coloring in some of these instances. There are modern makers who will put a Faux-Color on a modern alloy action.
If you closely read Marc's comments I believe he was not referring to the color hardening of the vintage guns as a "Fad" but rather the current abbuses of the practise by many. It is I think wise to note that many of the vintage makers did not recommend "Re-Casing" their own guns.

I have a lot of respect for Marc and Miller and their background. I have but one college level metallurgy course and a similar background to Miller's in shops plus some years reading met-lab results for airplane parts.

What I have noted is that modern low alloy steels of medium carbon content (4130,4140,4340, etc) have been successfully "case hardened" (generic term) or "carbo-nitrided" while maintaining a moderate core hardness. I ran across it on one of our critical airplane parts designed in the mid 60s and made until recently. The process used carried a proprietary name that escapes me at the moment. But, I do believe it is done and done on critical parts.

Where were you about 4 years ago when I got tarred and feathered over on AA for saying the same thing?

If it was original to the gun then with the proper understanding of what the results to the metal will be, I have no problem. In fact I have had it done and most likely will continue to do so with a few very select guns.

However, I have never understood the desire to subject every gun to this process. Yes, a few select custom makers turned out mauser actions with case coloring. However, millions of mausers were produced that were simply blued. I would have to assume that in the case of the custom guns, the makers selected the metals knowing in advance the final processes to be employed.

As for modern guns, I see no reason to case hardened them. Other finishes are available that can add to the aesthetic beauty of the piece.

Pete

Personally I have no objection to colour case hardening modern guns. We had this before onhere regarding cch of Ruger No1's.The late Mr Gaddy chimed in and mentioned that the colours appeared before the critical temperature. If you did it that way no alteration to the metal structure/strength would/should be achieved.

Proper cch of old mausers is a bit different, or the metal will move and once you put the barrel back on it will go past where it used to be and can slightly screw up headspace to and bolt bearings. Or it comes back without that but is soft and as soon as you fire it bolt will suffer setback with ensuing problems.Usual cch problems they are.
ASlong as the action was without cracks before cch(which you check with a cracktester) then I don't see any "major" safety worries on it, aslong as it's off correct hardness. Just annoyances for the guy putting it back together.

Now if you properly cc hardened a piece of 4140 yeah fair enough to me then the bloke doing it needs a bit more then a clip around the ears .
If you did cyanide hardening at only 20 thou deep that's how it's meant to be done.

There are so many cch mauser actions out there now , that if there was a serious safety problem with them it would be known by now.
The old mausers are meant to be made off low carbon steels like 1035(source kuhnhausen)and with the reworking one does on them you easily remove the existing hardening and have to do it again.
The old hardening wasn't always perfect either, ranging from 0.002" to 0.008" and a hardness off C25 and C26(source kuhnhausen again and more then believable to me).
Yes Kuhnhausen used the C scale instead off the N scale but having a rockwell C scale hardness tester seems to work for me to.

Now if you re cc hardened them you at times can get them harder then that if you're lucky.

Are we talking Mausers or shotguns? I am under the impression that many modern guns made of modern steel are case colored. RBL comes to mind and Siace is another. Is this different?

Arnold,
I had been under the impression (no pun) that the proper way of testing casehardened material was with some kind of micro-superficial testing and that Rockwell C scale testing would provide erroneous readings??? Aren't typical casehardened surfaces well above 60RC (if it could be RC measured)? 25RC seems really soft since most of the typical modern guns (4140?) I've tested were around mid 30's RC.

BTW, As Arnold describes, Oscar also gave me similar information when I asked about modern gun (medium carbon) steels. In fact, he specifically recommended having Doug Turnbull do this type of work.

I won't attempt to get into technical debates over whether case color hardening or Mauser actions is a good thing or not, but I currently have two of them, and sold another one about 12 to 14 months ago. These are German built by small custom gunsmiths in Germany between the wars. All three were built I suppose on reworked surplus Mauser actions, they all appeared to be standard M98 models with the military markings polished away, and all had very good color case hardening on the reworked and engraved receivers. One of the two I curently have has now been stripped down in preparation for having the original half octogan badly rusted barrel bore relined so as to make the rifle usable again, the remaining one is intact and has perhaps 40 to 50% or the beautiful case colors remaining. I am not a particularly good photographer, all I have is a point and shoot little digital camera, and I am not sure how good I could reproduce those colors. It is in the classic German sporting rifle style, butter knife bolt handle, side paneled stock with small cheekpiece, sling swivel band soldered to the barrel in front, nice open sights and claw mounts for scope. In my opinion, these are a beautiful classic German style of sporting rifle, and there's nothing faddish about the style, as it obviously has been around for quite a long time. I can recall seeing a modern M98 rifle by Hartmann & Weiss given the same treatment, I wish I could remember where those photos were. The Germans, who built the Mauser actions, BTW, apparently think nothing of case color hardening these actions, and have since at least either just before or just after WWI. I would say the proof is in the pudding. These three I have owned or currently own are far from the total number I have seen, I would have to say it would appear this procedure has been pretty common on reworked custom Mauser rifles for at least 80 years now.

Chuck,
I asked onhere before about what is best N or C scale and you came up with the micro superficial testing.
To my non metallurgist mind you won't be able to tell if the action is over carburized by using the micro superficial testing or not?
C scale yes, you go through the case, hence I have the C scale one and the fact that it was only 50£ on ebay (been recalibrated now).
And yes the 25C(was a 1930fn one)is really soft(unless I misunderstood his scale?), typically they are 55RC. Bolt 60rc
R.A Walsh uses the c scale for sure to, he notes that the case hardening on mausers wasn't done for strenght but for wear on the parts.Hard outside soft inside.
If I'm completely wrong I await to be shot down gracefully.

Arnold,
I can't recall what we discussed, but I looked in my Machinery Handbook and it provided at least 2 options. But it was less detailed than needed to be helpful. So, I googled the question and came up with a link you might find informative.
http://www.wilsoninstruments.com/products/rockwell/rockwell_scale_guide.aspx

I'm thinking someone recommended either the 15 or 30 N scale.

I'm not sufficiently knowledgeable to discuss whether there's a concern of over carburizing or what effects it can have. But, the Wilson Rockwell site does mention deep casehardening use of the RC scale.