Saving a Mauser wth setback lugs

[SixFive]

What am I missing on the heaspace not being correct? Never worked on and seldom seen the older mauser actions... mostly because of lack of interest.

I guess what I am asking is... if you are fitting a new barrel why would you not headspace to what you have now or set the shoulder back on the barrel you plan to use for proper headspace. I'm sure I have to be missing something but hoping to learn something here.

So these older war time Mauser action lugs are case hardened only, just the first .004 to .006 deep is hard, once the lugs set back you are through the hardness on them. You could re-set the headspace but as soon as you shoot it a few times the soft lugs will setback more and headspace will open again. So the fix is to get the lugs back to a hard state, then it will hold headspace.

Mausers were made by many countries, steels used varied as did the hardness of these receivers, but one thing they all have in common is some form of low carbon steel, some manufacturers used 1018 some used 1020 or the equivalents to these. Some Mausers were soft from the factory and some were hard as woodpecker lips, I have worked on hundreds of them over the years and there seems to be no real consistency. They "SAY" the Styer and Oberdorf were the best but honestly I have not found that to be true, it is catch as catch can.

Modern rifle actions use high carbon steels that can be fully heat treated through and through. Including stainless steels like 17-4 and alloys like 4140 etc...

You cannot use modern heat treat methods on Mauser actions as the actions are made of low carbon steel, they will not harden via those methods. The only thing you can do is introduce carbon as a layer of hardness = case hardening.

As an additional tidbit of knowledge. This lug setback is usually caused by
1. People trueing the lugs on a lathe and cutting the hardness out of them
2. People over lapping the lugs cutting through the hardness
3. re-chambering in cartridges these actions were never designed to handle
The Mausers really did not have issues if they were left alone and shot cartridges with pressures they were designed for. We are talking WAR Mausers, not commercial Mausers.

Most people just toss them when set back happens, it is expensive to have them case hardened by a pro shop, fixtures and jigs must be used to eliminate warpage. My method\test is to JUST case harden the lugs themselves as this is where the problem is. We shall soon see if my experiment works.

 

[SixFive]

I have success! The Styer M98 project was finished today and test fired with no issues. Started with a minimal load of IMR 4350 39gr and pushed it to the 45gr with 140gr bullets. No sign of setback or head space changes. Seems like I saved this one!