I've read several posts about heat treating and almost always about '98 Mauser actions. I've bit my tongue hoping to learn something from others but (knowing how a little knowlege can be dangerous) would like to help clarify a few things and ask specific questions.<br /><br />First I'd like to separate heat treating and case hardening. Heat treating is any heating process to (primarily) steels that alters the grain structure and that includes annealing. Heat treating usually (but not always) means the process of hardening and is usually done in two steps. First the steel is raised to (about) 1550 degrees and quenched, and then heated again to a lesser temperature (anywhere from 1000 degrees to as little as 400 degrees for the purpose of drawing the hardness to the steels working range. 4140 as originally hardened can reach 60Rc but is much too brittle and is then drawn to it's working hardness of (about) 40 Rc.<br /><br />In order to "heat treat" the metal must have at least .30% carbon and 4140 has .40% carbon ...the last two digits of aisi steels.<br /><br />Case hardening can be done to any steel regardless of it's carbon content but is usually done to low carbon steels that can't be "thru" hardened. Steels like 1018, 1117, 12L14, and A36. Case hardening is accomplished by putting the steel in a high carbon atmosphere (or salt bath) for up to several hours. Typically carbon is absorbed thru osmossis into the surface of the steel at about .010 deep per hour and many case hardened surfaces are only .005-.015 deep.<br /><br />Case hardening does not add strength to the action (or extremely little) The case is a fine wear surface and when polished provides a super smooth way surface for bolt lugs. It can also be used to decorate when case coloring is done.<br /><br />Cold rolled steel can be anything from very low carbon steels such as 1008 to 4140, 8620 and just about any chemistry steels are poured in. Cold rolled is a process of finishing bars (round or flats) and is not at all indigenous of low carbon steels.<br /><br />Now where the big question comes in.....I've built about ten or so custom guns from Mauser 98 and only one of them was case hardened by the manufacturer. All the actions I used was either German or Czech. The one that was case hardened was a fine 1937 action by J P Saur of Germany. All the others was soft and I don't have a clue as to what the chemistry of these actions was except to say that one past attempt to harden and draw a '98 gained nothing in hardness as I assumed that meant that the carbon content was low. <br /><br />The rebuilding of these actions was to hi intensity cartridges such as .220 S, .25-06, and .300 Win Mag. All functioned without any problems at all and with absolutely no heat treat whatever.<br /><br />Given all this I'm under the impression that unless one would like to case color or case harden the action to achieve super smooth feeding of the bolt through the action that there's no need to thru harden the actions.....and as a matter of fact it just can't be done because there is so little carbon in the steel to permit it.<br /><br />Given all this...would someone explain where my thinking went south and what the chemistry of '98 mausers actually is.....

Good question. I have also wondered about this, and the re-heat treating of M98's. P.O. Ackley has some info on their metallurgy but hopefully some that lurk here can give us some good info? My limited understanding is that they were selectively (differentially? don't know the proper terminology) case hardened at the points of highest stress and/or wear. Are there any good books out there that describe what the Germans actually did?
C.G.B.

I'll take exception to the statement "case-hardening adds very little strength". It is at least misleading, if not downright wrong.

Now, your typical color case-hardening adds very little strength. It can sometimes be only a few molecules thick. It is often done strictly for looks. Your statement applies to color case-hardening.

But carburization depths of .035 and thicker can easily be achieved. This gives you a skin of high-carbon steel wrapping the low-carbon body. This skin can be heat-treated to a reasonably high hardness. This will add both strength and brinnelling resistance as well as wear resistance to the unit. How much this affects the yield strength of the whole unit in KPSI is problematic and of little interest. (But a hardened steel plate .035 thick is a substantial chunk of steel.)

What it does do is prevent the lugs from brinnelling or "setting back" into the action. This feature alone makes the carburization worth the effort IMHO.

Paul Mauser did nothing without a reason, and all early Mausers came carburized and heat treated from the factory. That alone should carry a lot of weight. If you don't affect this layer significantly when you lap the lugs then you should be OK without doing the whole process over.

I'm not an expert in heat treating and don't intend to become one.

Adios,

Vapodog

I just took this off of the Brownell's site, and what I am wondering is if a combination of case hardening and cyro treating might be just the ticket for those 98 mauser actions.

Cryo-treated Tools - Why They're Better
By: Andrew Swan

You've probably heard the big claims about Cryogenic treatment and have probably been wondering if it really makes a difference. That's because Cryogenic treatment has had mixed to downright bad reviews in the shooting community.

When cryo-treated barrels were first introduced, you would have thought someone discovered the magic cure-all for perfect shots . . . that we�d be seeing groupings at a thousand yards you could cover with a silver dollar easily. Unfortunately, results didn't live up to the expectations or the hype.

But it's a much different story when it comes to Cryo-treated tools. Cryo-treated tools won't make you a master gunsmith, but your cryogenically treated tools will last longer � saving you money in the long run. Cryo-treatment has three main benefits:

increases dimensional stability
removes stress
improves wear and abrasive resistance
How does Cryogenic Treatment Work?
Cryogenics is a one-time, irreversible treatment that permanently changes the entire molecular structure of the material being treated, not just the surface, creating a denser molecular structure, resulting in a smoother contact surface area that reduces friction, heat, and wear.

There are two types of Cryo-treatments - deep treatment and shallow treatment. The deep treatment process involves the slow cooling of materials to temperatures of approximately -300� F and then slowly re-heating them to varying temperatures, depending on the material. This is much preferred over the shallow treatment, which only cools the material to -120� F and does not give the full range of cryogenic treatment benefits to the material.

One of the big challenges with cryo-treatment is that you can�t tell what�s been treated and what hasn�t by examining the tool. But, as they say, �beauty is more than skin deep.� What you can�t see will make a significant difference. Cryogenic treatment dramatically increases the tool�s durability and wear resistance. Internal residual stresses are released and result in increased tensile strength, toughness and stability.

Real Life Uses. Real Life Results.
Using cryo-treated tools can reduce perishable tooling costs by as much as 25% to 30%! Machine downtime and maintenance costs can also be dramatically reduced, increasing productivity and lowering production costs. Treated tools typically increase production by two to four times compared to non-treated tools, and treated components may be ground after treatment and the benefits of cryo-treatment are retained.

Cryo-treated tools may be re-ground more times before falling below minimum acceptable specifications than non-treated tools. Cryo-treated tools require less removal of material to restore the cutting edge, thus extending the life of the cutting tool.

Polartek Cyrogenics reported to Brownells that one of their customers, a pork packing plant, came to them for help in reducing the cost of replacing saw blades used in processing meat. The chart below shows the results of three different blades.

Blade Type # Hrs use before treatment # Hrs use after treatment

13" Circular 6 with 5 sharpenings 36 with 5 sharpenings

18" Circular 640 with 4 sharpenings 2400 with 4 sharpenings

Serrated Cut Off 6 with 5 sharpenings 30 with 5 sharpenings



Annual projected savings for these three blades alone is a whopping $123,256! This is just one example from one customer, but the research shows that this is not a statistical fluke � cryo-treated tools last longer and save money.

It is true that cryo-treated tools cost more than untreated tools, but the cost difference is more than made up in tool life and increased production. Cryo-treated tools will be less likely to give you an uneven cut due to their molecular hardness, resulting in smooth, professional cuts the first time.

Now at this point, you may be saying, �Sounds great, but how can this help my gun shop�s bottom line?� Let�s turn to an expert, one of Brownell�s gun technicians Mike Watkins. According to Mike, cryo-treated gunsmithing tools DO live up to the hype.

�I was installing a Novak rear sight on a hard slide and the 3/8 inch end mill for the initial flat cut was better than the results I have been getting with carbide.� Mike goes on to say, �The cryo-treated .495 dovetail cutter cut easily and smoother than I expected, as the slide was so hard that a file would barely cut it. I have been testing cryo-treated mill cutters, drills, and taps and have seen an increase in life expectancy and performance.�

Cyro-treated tools may give you the �edge� that you are looking for. Longer periods between sharpenings, easier cutting on hard metal, longer tool life, and reduced tool cost are a few of the benefits of using cryo-treated tools. The chart below compares shallow treatment performance gains vs. the deep treatment performance gains.

Cryogenic Tempering - Documented Gains For All Types Of Metals

AISI # Description of steel (-110 F) (-310 F)

D-2 High carbon/chromium die steel 316% 817%

A-2 Chromium cold work die steel 204% 560%

S-7 Silicon tool steel 241% 503%

52100 Bearing steel 195% 420%

O-1 Oil hardening cold work die steel 221% 418%

A-10 Graphite tool steel 230% 264%

M-1 Molybdenum high speed steel 145% 225%

H-13 Chromium/moly hot die steel 164% 209%

M-2 Tungsten/moly high speed steel 117% 203%

T-1 Tungsten high speed steel 141% 176%

P-20 Mold steel 123% 130%

440 Martensitic stainless 128% 121%

430 Ferritic stainless 116% 119%

303 Austenitic stainless 105% 110%

8620 Nickel-chromium-moly steel 112% 104%

C1020 Carbon steel 97% 98%

AQS Graphite cast iron 96% 97%

A-6 Manganese air work cold die steel 73% 97%

T-2 Tungsten high speed steel 72% 92%

Source: Dr. R.F. Barron, Louisiana Tech University



Brownells will soon be offering a selection of cryo-treated tools that are treated at -320?FS, which provides the most improved tool performance in the industry. We�re in the process of creating a way to mark the tools so you�ll be able to tell your cryo-treated tools from your untreated tools.

Watch for them in the near future; you're going to love the results.

Blue

Blue, thanks for the Cyrogenic treating article but at this stage it's not germain to the issue of how folks are currently heat treating mauser actions.

For those gunsmiths out there that send the actions off to be heat treated can you say what specs you ask for?...are you getting them case hardened.....and if so how deep?...What hardness number...either 15N, 30N, or 45N

I'm interested because I haven't ever heat treated a 98 mauser and if I should be doing so what specs should I request?

Why don't you just call Blanchard's and ask them, the ones who do it?



All you have to do is tell them how hard you want it and that is how hard they'll make it.



Blanchard Metals Processing CO

1115 Pioneer Road, Salt Lake City, UT 84104

(801) 972-5590



I had an m1909 redone to RC40, both receiver and bolt for my .300 Ultra.

Twice in one day, Hand me the flack jacket! While attending the School of trades in Denver, We were told that any 98 rebarreled to a modern caliber should be re-carborized .030 to .040 deep so the surface hardness was around 36-40 RW C. The bolt a few point higher 40-44. They converted more than just two or three. Later when I opened my own shop I built 2 rifles chambered for 270 Win. and fell into the mind set that I now refer to as "how can you re-heat an action if you don't have a clue as to what it's made from" One was a 1909 and one a Radom. I had the rifles back in my shop years later and both had been set back enough that I had to set back the barrels the required amount clean up the lug seats and then sent both actions in to be recarborized and have not had a problem since(REMEMBER SAME REAMERS, SAME GAGES, SAME RIFLE). Do you know of anybody that has a 270 that won't try to get 3100 fps with a 130gr bullet? Ray sure won't leave the 404 at original speeds. The number of rifles I have had in my shop for some sort of repair or restoration that have set back is long indeed. This list would include the hallowed 98 square bridge actions, vz-24, 1909, 1908, and one FN in the white straight from the factory that I failed to check with the rockwell tester. I chambered the FN to 300 Win mag and it set back .015 in less than 200 rounds. It has since been hardened and to my knowledge has not move to the rear at all.Take it for what it's worth.

I have every 98 that I now use annealed dead soft, do 90% of the machine work that is required. Then it is sent in to be re-carborized as described and then finished up. Some 98 actions are probably OK to use as is the 1935 being one of them. But why take the chance and why waste all those end mills on an action that is glass hard on the surface or have to eat the repair when it shows up back in your hands.

I did have two 1909 action destroyed to get an idea of the steel composition. The results were as predicted and I now use the 1909 for any project that requires a 98 in a standard length Magnum, no I don't use them for the 375 H&H or similar lenght round as the action just gets to sloppy for my taste. Russell Wilkin the shop manager at H&H (ever hear of them?)requires all bolt rifles built on the 98 actions to be re-hardened. Go figure. Got to give my girl a bath!

I have been following the heat treat discussions closely since I love build guns on 98 actions. After what I have heard here I am convinced that heat treating is the way to go. Darcy Echols brought up in his post that he anneals all actions he works on. That makes a lot of sense to me. That hardened surface is a bugger to clean up.

But that brings up another question.

So how do you properly anneal an action?

It would definately nake it much easier to work on annealed.

vaodog,
You are doing a good thing in getting this topic out for discussion. Mr. Echols has given us a very good method to follow. Many people do not realize that you must fully anneal steel before you can harden it to a different state.
You are limiting your through-hardening examples to a small sampling of steels. There are steels that must be taken to over 2000F before quenching. There are a lot of steels that are carburized, leaving them with a hard case and a very tough core, 8620, 9510, etc. Some of these steels are used in currently made custom actions. These steels have additional alloying elements beyond carbon and iron. The low carbon steels like 1010, 1018, 1020, cannot be made tough or hard below the surface treatment. But they are very stable after casehardening so are chosen for that characteristic.
I suspect that millions of Mauser type actions were made like Twinkies, "hard on the outside and soft in the middle". They worked for the intended purposes but are at risk if used in the original state for high pressure cartridges that were developed decades later.
A very good source of information for us that do not have an engineering background is found in the catalogs from steel companies. Ryerson, Pacific and others have a wealth of knowledge but are not available at no cost. Another good source of info is the later Machinery's Handbooks.

When Weatherby was building rifles on FN actions prior to 1958, Roy Weatherby ordered specially heat-treated actions from FN, and even some of these rifles will exhibit lug setback.

There are also specimens of new-in-the-cosmoline 1909 Argentine Mausers that exhibit lug setback, and these rifles were only test-fired at the factory!

When Rigby rifles were still being built in London and Paul Roberts was in charge, he also insisted that Mauser actions were to be re-hardened as standard proceedure. Actually, the British paid great attention to this aspect of rifle construction for many years. Even before WWII, when the great British gunmaking houses were ordering commercial Mauser actions direct from Germany, these actions were ordered with special heat-treatment, according to the riflemaker's specifications.

I'm just a consumer, but I do not trust surplus Mausers as they come, at least for the most part. As far as I'm concerned, if a gunmaker refuses to reharden a Mauser that's intended for a modern, high-pressure cartridge, I take my business elsewhere.

Dave Miller is another riflemaker who insists on re-hardening Mausers, states about the same case as D'Arcy does, and like D'Arcy, at least as far as rifle mechanics is concerned, I'll put Dave's credibility on the line with anyone..........

AD

I am a metallurgist so perhaps I can shed some light on the subject.DArcy has the right idea.When I was at the same gunsmithing school I worked on my own Oberndorf '43 M98 .It had been case hardened but a poor spotty job.Wartime quality had already fallen.There was a heat treater in the area who did the work for the school so as a metallurgist I was concerned about just how they did it .I don't remeber the specifics but I was satisfied and had it redone. You can case harden to any depth you want from very shallow for just wear resistance to very deep for added strength.Btw your automobile bearings and gears are case hardened for both wear and strength.A low carbon ,low alloy steel should be case hardened for added strength. The final hardness levels mentioned by DArcy are appropriate.....As I have said in a number of previous postings --- most of what you hear about cryogenics, especially about guns ,is pure BS.It's sponsered by and pushed by companies that sell the service.It isn't new ,in the old days we called it sub-zero quench, and it has application in some tool steels .But the rest of the stories are just that.

So far all of my personal questions have been well answered. Mr. Echols comments are the best I've ever read on the subject because they are in line with my education in heat treating and metallurgy.

I said that most mausers was not hardened.....this based on a J P Saur and the eddystones (p-17) that was very hard. A file could not scratch them. I frequently "round up" mausers with a file and have no trouble at all.....but of course at 40 Rc they can still be easily filed.

Typically case hardening is .010 deep and yes it certainly can go up to .06 deep given enough time.

So heat treating a mauser action is the process of
1. total anneal
2. Carburize .03-.04 deep
3. Harden and draw to (equivalent) Rc 40....it's actually measured on the 30N scale

I think we're getting somewhere now.

Thanks to all who have contributed to this subject....it's been an education to me.....I'll certainly heat treat any further military mausers I convert to a sporter.

Mike, that's correct. I had trouble with the stock finish on a Miller Marksman under wet weather conditions, which is the sort of problem I would rather not deal with. That's the only real gripe I've ever had with Dave's product. Otherwise, function, accuracy, durability, reliability, and quality were absolutely tops. What sort of stock material or finish procedure he's now using on the Marksman I can't say, but it's probably better, simply because Dave isn't the sort of guy to ever sit still or rest on his laurels.

I became an Echols client based on D'Arcy's merits as a gunmaker alone, not to mention that fact that he was offering the option of a fiberglass stock, which I prefer for hunting -- at least much of the time. There are certain things I like even better about D'Arcy's product, including his magazine system, scope mounting system, etc., plus the fact that he employs Tom Burgess bottommetal, which I like better than the Blackburn product Dave uses, then modifies. D'Arcy and I are also the same age, connect well and are friends, share the same sense of humor, and Beth and I consider him as part of the family.

Even so, Dave's metalwork, stock design, and quality of refinement and finish detail is truly equal to the very best in the world. He's even gone so far as to have technicians from Remington and Winchester visit his shop in order that he might gain a better understanding of what can or shouldn't be done with action modifications, etc. A visit to Miller's shop is, well.... an incredible experience, to say the very least. Every tool is in its place, superb equipment is abundant, Curt Crum is a fantastic gentleman and great artist in his own right, the supply of truly fine walnut is incredible, and Dave's office is full of fine trophies. I love Tucson, anyway!

I'll never forget visiting a small rural gunstore (a pretty good store, really) near here a few years ago, which was owned by a repair-type riflesmith who also built custom rifles of his own interpretation. Another customer had a copy of "Gun World" on the counter with a story about Dave Miller rifles in it, and this customer was telling the gunsmith/owner about Dave's product as he had read about it in the magazine. The gunsmith gruffly piped up that he could build "anything that Miller guy can build", and he really meant it. I didn't say a word, but that character's custom product wouldn't take third prize in a two-entry contest, and he wouldn't even be qualified to install recoil pads in Miller's shop..........

AD

Allen

This might be getting too nosy, and if so I don't mind you telling me so, but I would be curious to know if you actually told David about the problem, and what David might have said about it.

Blue

For he past 29 years I have been either learning about or solving problems associated with the heat treatment of steel. I consider myself to be knowledgeable but not an expert on this subject. Also, I am not very knowledgeable about gunsmithing, so bear with me here.

On the subject of Cryogenic or cold treatment of steel; I have done this and know what is happening to the steel when this is done. Generally, I will say that this process is beneficial when heat-treated steel has a high carbon and high nickel content as these elements are austenite stabilizers. Carburized or case hardened steels will benefit from cold treatment. Cold treatment is �120F or lower. So what I am saying in regards to guns is; barrels are not heat treated and would not see any effects from cold treatment. If your bolt or action is carburized and hardened (quenched), you may benefit from cold treatment or cryo is about �385F of immersion in liquid nitrogen. But you can get a good carburized case without cold treatment. Tempering should always be done after cold treatment. I really do not see were cold treatment of steel in gun components would be that beneficial.

Basically, you cold or cryo-treat steels to improve the uniformity of the case microstructure of carburized components. If your steel component is not carburized, cold treatment will have little or no effect (castings are another story), we are talking about wrought steel here, stuff guns are made of. Cold treatment reduces or eliminates retained austenite in carburized case microstructures. This will increase hardness, strength, wear resistance. Good stuff ! But if you are only hardening your gun action components to 40 to 45 HRc (I consider that only medium hard), you do not need to carburize, so you don�t need to cold treat either.

I am going to guess that a good material selection for a bolt and action would be 4140 steel. This will quench out at 55 to 59 HRc and you temper it back to your desired 40 � 45 HRc and you are good to go, no cold treat will improve these components. Now a good use of cold treat is high performance gears; Like what you use in a racecar transmition. I would want a case hardness of 60 HRc, a case depth of 0.03� (effective to 50 HRc), a case microstructure of 98% tempered martensite (cold treat to get this) and a core hardness of 35 HRc.

Sorry for the long reply, I could go on and on on this heat treat thing, maybe no one will read this far anyway. But I do have to admit that I like to play with the LN2 and see it�s effects on carburized steel cases, I recommend it sometimes as a fix for poor heat treat practice. Maybe this has shead some light on the subject and not further confuse it.

JBM,wrought steels ,what guns are made from ? I guess you never heard of Ruger who casts almost every part and the many other makers who do the same.It isn't whether it's cast or wrought but the alloy used.Ruger uses mostly 4130 and 4140 as I remember.As far as cryo for improving poor heat treating ,do it right the first time. At this point in time there is no proper scientific metallurgical research which shows that cryo does anything except reduce the amount of retained austenite and that will only be found in high carbon, high alloy steels at high hardness.

mete. I guess you are saying you agree with me. cryo does not help gun type steel. It will reduce retained austenite in a case micro. Retained austenite is soft so when it converts to martensite which is harder the case will be harder and stronger. But when it converts it is untempered and can cause brittelness and cracking. I agree do the heat treat right the first time, but if they did they would not need us as much. Not a perfect world; heat treat I mean.

Eldeguello, Considered as a whole there is not enough difference in the steel recipe for military '98 mausers. The reason for this is that machining with a predictable cutter wear, smoothness of finish from the machining and the final carburizing process leading to proofing all entered into the acceptance of any lot of steel. The steel does not exactly correspond to North American AISI SAE or ASME lists and chemistry's. The closest we have is the 1100 series. Prior to WW II there was a group called "Machinery steel" If you can find an old Ryerson book of that era you may find that this group had about 3 varieties from arouind "18 carbon ,25, 30 and 44 carbon". Starrett used the low carbon steel to make many of their tools "case hardened in colors". Others did similar things with it. The Various carbon grades of this steel is still available in various parts of Europe. For the Mausers the Spec was 27 to 33 Carbon. The significant alloying agent was Manganese. There seems to be very little difference from as early as 1901 to about 1942 in a carbon range of 27 to 33 and a Manganese spread from 115 to 140. The Manganese helped in the carburizing process because it allowed deeper penetration of the added carbon and softened the boundary definition in the carburised case. A smoother transition from case to core if you will. This also allowed a finer grain structure, and because the manganese tends to make up for the bad effects of too much sulphur ( up to a point) the Sulphur number could be higher allowing for smoother surfaces from machining, less wire edges to be trimmed at corners and so on. Carburizing these, particularly in the carbon monoxide gas process,is quite straight forward and does not require fancy or exotic methods. For those who have had readings made and point to all sorts of trace ammounts of various other elements I have to say that in carburizing these it makes damned little difference. Those actions made close to Czecoslovakia and or in that country will often have many elements in the mix and some of these can be said to add to the strength of the receiver and bolt.
This had more to do with the cokeing coal used to make the original pig -iron. These elements were sucked up by the iron in the melt, and could include Uranium, and Zirconium among a fairly long list of neither add nor subtract from strength elements the combination regarded as a whole entity. The Argentine made '09s do seem to be different. In a heat lot of 10 The as quenched Rockwell was noticably higher and required almost 100 degrees more heat (F) to achieve the desired Rc hardness. Conversely some crude Spanish made actions complete with Mauser Logo and "standard modell" plus a certain importers mark had to be cooked for additional time to achieve desired hardness. Subsequent test of another from the lot indicated 15 carbon steel. The machining was crude enough to indicate it had never been to the Fatherland. Experienced heat treaters check the hardness after quench to determine the correct temperature for the temper draw. In some schools the process is then known as heat-treating. The original method was Pack hardening. The carbonaceous material at the heat used liberated carbon monoxide gas which was absorbed by the iron. At quench this material flaked off in the quench medium, This was saved and applied in areas not needing great depth or hardness of case. New material was used in the locking lug area the bullet ramp and underside flat up to the recoil lug and also on the extracting cam of the bridge. Recycled material was used every where else on the exterior, but recycled plus new material was applied to the feed well and most of the rest of the receiver subject to wear from the bolt. The tang flat where the trigger humps rolled also got a good gob of new material. This was labor intensive. To go to Copper plating as a stop off would take double the time and was totally unnecssary. Same for the baked on copper bearing paint that the German's had available. The early powders used in Europe did not have the same burning characteristics as did Brit. Cordite or the American cylindrical powders. translating a Rockwell number to yield tables in "the book" are fine for static loads but not worth a damn for the Dynamic loads produced by modern powders particularly in so called reduced loads- the 25-06 being one come to mind that can produce great violence so loaded.

That post just cleared the centerfield seats and is out of the park.

Can I hear an "Amen" from the congregation?

Well, Now I know the reason why my good friend's 1909 Argentine in 25-06 developed pretty bad lug setback and had to be completely redone after only about 200 rounds through it, and I also know why a couple of 1909s that I had reheatreated at a place that didn't know what they were doing warped and cracked!!!!

AMEN

Blue

AMEN is right.......

Tom, that post was absolutely fantastic, one of the best I've ever read, and I'm astounded that you took the time you did to put it together. Someone's bound to claim you're wrong on one thing or another though, and will probably give you heck for it, so brace yourself!

Let's see......... We have D'Arcy Echols and Tom Burgess contributing on the same thread, which just might be a first in internet history, plus metalurgists, etc.

Amazing......

I think I'm going to print this thread out and save it for posterity!

AD

Blue, yes I told Dave about the problem, and he acknowleged it, but I eventually sold that rifle, plus one other that I never used, at a profit and that was the end of it. Finish problem or no, I'm still a big fan of Dave's work, and I always will be.

AD

Guess I wasn't so far off base starting this thread.....I actually thought I'd be laughed at for asking such dumb questions.....

That question was settled for me some years ago, and come to think of it, D!Arcy was the individual that got me on the straight and narrow...but there are lots of well known gunsmiths who will lead you astray and some might even post here from time to time...

Well Ray, you know what they always say about people who lead you astray:



"The only fool bigger than the person who knows it all is the person who argues with him". I sure found that out around here.



Blue

With all of these renouned rifle builders on this thread I would like to post a question sort of on topic. Can you "color Case Harden" any bolt action receiver...."for the look" i.e. a pre-64 mod 70 ? or would if become to fragile (unsafe at any speed)

You can fake it on any receiver with a torch which produces just oxide colors.However to actually color case harden requires knowledge of the type of steel, hardness desired etc.

Check with Turnbull's for the color case. He did a number of Dakota's #10's and 76's and these are, or at least they were when I worked there, 4140. I've also seen some Ruger #1 rifles done by him. I talked to Turnbull at a show in Cody and he assured me he can color without screwing up a high carbon receiver. I'm not sure if a metalurgist would agree here though?? Turpin's book "Modern Custom Guns" has many pics of his personal 7mmDakota #10 that was colored by Turnbull. I stocked the rifle before coloring and during final assembly the action had mooved a little. The extra clear coat didn't help fit the inlet either.

gunmaker

Doug does not Color Case Mausers anymore.

That is a fact.

He turned mine down with the broader statement that he doesn't do any restoration work on Mausers at all.

I don't know why, though. Maybe all the Colts and Winchesters are keeping him too busy.

That and I believe warpage to be a a big factor in the color case process. Unlike, gas carburization.

I know of two Dakota #10 actions that cracked/broke after color case hardening. If you are familliar with the action, one broke at the junction of the top rear tang and the post going down to the lower tang. The other cracked through the safety recess. Each cracked when the draw bolt was being tightened and one of them on the very final assembly by a very talented gunmaker.
4140 is not the steel for that process.
I also saw John (restinpeace) Hackley drop a red hot Ruger #1 into a quench tank at a gunsmithing school seminar (I was there teaching, not attending). I shuttered more deeply than the metal did. Just because folks do these things doesn't make it right.
Tom, is there someone you recommend to heat treat Mauser actions?

JBM,

I must agree with mete on this one. Furthermore, cyro treatment doesn't do squat for high performance case carburized gear steels. Specifically, SAE8615, SAE8620, SAE8625, SAE4320, SAE9310, SAE9317, 17CrNiMo6, 18CrNiMo7-6, a few proprietary European recipes, and the list goes on.

There just isn't any retained austenite to get rid of. These alloys ain't hyper-eutectic! Even if minute amounts of retained austenite did reside within the martensite structure of the case, big deal! The case is for wear resistance ONLY. The core carries the load, and before anyone starts talking about pitting, pitting is a Hertzian stress failure and is initiated in the core and propagates to the surface, IT IS NOT A CASE FAILURE, and pitting's technical name is contact fatigue. Essentially, the core yields and the case looses it's support and flakes off.

To help the technically challenged, think of it like this. You just removed all the dirt from under the foundation of your home, what happens (the foundation cracks big time). The concrete is much stronger than the dirt, but without that dirt supporting it, the concrete cracks and RIGHT now!

Now with HIGH carbon HIGH alloy tool steel, cyro is a big fatigue life improver!

Personally, I think SAE4140 sucks. True it is better than SAE1008, but that is about all I can think of to say good about it. I can get equal to or even better fatigue performance from SAE1050 when properly heat treated. Besides that the impact strength of SAE4140 sucks, when compared to SAE8620, which when case carburized, is more wear resistance, and just as strong in the ol' tensile tester. More importantly, case carburized SAE8620 has a hell of lot higher impact strength! This is kinda important, when one considers how a rifle's action is loaded.

Heck I would take SAE1340 over SAE4140 any day. Much tougher, heck it is much tougher than SAE8620, and is really right there with 17CrNiMo6 and damned close to SAE9310. Must be why all those high impact steering components are made out of SAE1340 forgings, this is particularly true of off-highway applications.

Well, the obvious question then would be: why aren't the gun manufacturers using these better quality steels rather than using 4140?

Blue

Because 4140 is a cheep standard, albeit applicable to guns. Interesting aside.... I read somewhere, and I have been trying to dig it up, that for the winchester low wall/high wall that browning has been making, they make the blocks from 1045, which is fine but it goes to show the mentality of the material selection. It was written in some obscure browning literature I have. Much of this is determind by price/ease of manufacturing & heat treating if any. The diff between 1045 and 4140 isnt much in the way of strength or even wear (and can overlap by poor heatreating methods) if a person considers the life of a firearm.

There's not a lot I can add to this discussion but I'll try anyway.
It is possible to carburize to a depth exceeding .100" (1/10"). I'm a real fan of plain bone meal as a carburizing agent (that is, the charcoal made from the bone meal). I also like powdered milk. The high calcium content seems to help. Properly carburized, low carbon steel is no longer low carbon steel on the surface and may have over 80 pointsof carbon. As hardened, with no draw, this surface can be in the low 60's on the Rockwell scale.
There is a lot of variation in 4140 as it is purchased and this variation can be seen on the spec sheet if you get one with your order. I have had some heat treated stress relieved 4140 which was very, very high in sulphur, something on the order of 2% if I recall. This machined beautifully and was fairly stress free (or at least stress limited)and smelled almost like malleable cast iron when cut.
I have found the heat treating of 4140 to be a bit of a challenge at times. It hardens fairly predictably but stress fractures occur quickly if it is not drawn right away and sometimes even if it is. I learned early on to warm up the oil bath before quenching 4140 pieces. Most especially those with complex shapes. I once hardened a shaft which featured an integral gear and splines on each end (and which took some time to make). After quenching I checked it and it was pretty damn hard. I set it on the bench and was admiring my handiwork while deciding exactly how I was going to draw it when, suddenly, one of the teeth jumped right off the gear! Then, with a little "tink", it split on one spline. Luckily I had made two and on the next one I had the oil warmed up considerably and put it in the drawing oven right away. It's still in service 6 years later.
For wear resistance I prefer case hardened mild steel since it can be made very hard yet has less tendency to crack. For pieces requiring impact resistance I like EN30B which is a high nickel alloy. This is not real hard but is much stronger than 4140 in any condition and is very impact resistant. Wear properties are not bad either. Machining properties aren't so great though and it's a bit tough on tooling.
Alloys like 4140 can be colored but they will not tolerate any sortof case hardening process.
I've seen a Hartmann& Wiess receiver which broke up when color cased. I suspected this might have been an alloy receiver which caught the treater by surprise butI can't say for sure.
I've been planning to carburize and harden some Mausers just to see what can be done but this is only one item on my "going to" list so who knows when it might happen.
Annealing is no big deal and I accomplish this by simply putting the receiver in a crucible or wrapping it in stainless foil. In with the action, I put some paper or bone meal just to use up the oxygen (no scaling) and then heat it to around 1350 then let it cool. It is then dead soft and pretty inert. I once annealed a color cased single shot which had warped badly in the process. The hope was that the attendant stress relieving might "unwarp" the receiver. No such luck, but at least it could be straightened comparatively easily.
I confess that in most of this I am flying by the seat of my pants with little in the way of preconception. In other words,I don't know much to start but I teach myself a lot. Just when I think I'm gaining in the knowledge department though, I'll inadvertently read something written by someone who actually knows (I try to avoid this so as to keep my self esteem level up) and I'm shot down like a duck. Regards, Bill.

Bill... do you do pack hardening with your milk? Dad and I just finished a new gas forge for small parts, chisles and knives for me, but it has a heat/wool liner and wont be for case hardening work. I drew up a gas forge made with soldering brick, but I doubt I will make it this year. I had made some pack boxes with large flanged lids to wack the tops off, but havent tried them. I thought... maybe make a close tolerance piston in which the ram is supported by a templax pill in the center of the work (which is supported by the pack material)... when the templex pill melts the weighted piston moves slightly down. So what about gas leak? well if that became a problem the pack box would be wrapped in SS foil tensioned with binding wires... so the "sheets would go down" sorta speak