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!