OK, start with this D' Arcy Echols and Tom Burgess.
D'Arcy extract:
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!
TomBurgess extract:
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.
Last edited by butchlambert1; 09/13/16.
