View Full Version : Mauser Heat Treatment & Steels

May 19, 2002, 12:20 PM
What can anyone tell me about the steels used in Mauser 98 actions and how they were heat treated? In machining an action from scratch would you recommend 4140 or 8620 steel?

Unkel Gilbey
May 22, 2002, 01:58 PM
Off hand, I cannot give you exact info, as my references are about 15 miles from me, but I can give you generalizations and suggestions.

When talking about Mausers, I'm sure you understand that they were making them in all sorts of different versions and from different factories for quite some time. There had to be variations in the materials used and in the heat treating processes that were utilized.

Jerry Kuhnhausen's Mauser books gives a fairly concise history and explanation about nearly all these different variations. He will tell you which ones to look for, and which ones to avoid. This is in case you were thinking about modifying an existing action. I wouldn't recommend this though, as unless you have lots (years) of experience in heat treating metals and have access to the various different methods for heat treatment, you are playing with a jug of dynimite. Heat treating a Rifle receiver isn't something you can do with a propane torch!

A look into my Brownells catalog show that Dakota Arms makes their actions out of 4140 stainless. This goes for every action they have listed from their pre-'64 Model 70 copy to their #10 single shot. Smiths Industries M14 receiver is cast from 8620 steel, and Meacham's Hi-wall copy is also made from 8620 steel (CNC machined) in is case hardened.

I would say that which type of steel you choose would be dependant on a couple of criteria; namely tooling, availability of material, and experience. Keep in mind that whatever you end up with, it will have to be heat treated, and this (again) brings into question what your resources are.

Quite a daunting endeavour your are taking on. I wish you luck, but caution you to do your homework and get advice and directions from those who've already been down this road, folks such as engineers at Winchester, Remington, Ruger, Dakota, etc.

Good luck, and don't blow yourself up!

Unkel Gilbey

Jim Watson
May 22, 2002, 05:55 PM
According to Hatcher and Ackley, real German Mausers were made of plain carbon steel, somewhere close to 1035; .3 - .4% carbon, .6 - .9% manganese. They were surface hardened for wear protection. As deHaas said, Mausers get their strength from good design and material distribution, not expensive alloys or elaborate heat treatment.

I am not a gunsmith or machinist but from what I have read, the DIY gunmaker these days is better off with chrome moly like 4140 or 4350. It is available pre-hardened if your tooling can hack it, so to speak. Otherwise you will have to have a relationship with a heat treating company.

Some of the deHaas books go into making actions. Although he was a single shot buff, there is probably good information there on materials and techniques that would apply to bolt actions.

May 24, 2002, 02:06 PM
"A look into my Brownells catalog show that Dakota Arms makes their actions out of 4140 stainless. "


Are you sure that is what the book says ?

May 28, 2002, 10:17 PM
Thanks for the help so far, folks. What I'm really looking for is:
"does anyone know how deep the carburizing goes?"
I am on a limited budget and dont want to hardness test my only spare action.

George Stringer
May 29, 2002, 07:48 AM
It varies from action to action from just a few thousandths to .035" thick. According to Kuhnhausen most are .002" to .008". George

Unkel Gilbey
May 29, 2002, 02:53 PM

I went back into the catalog and reviewed what the specs for the Dakota Arms pieces were and they infact said "4140 Steel" instead of what I had reported as stainless.

I guess that the 'in the white' pictures in this catalog lulled me into the assumption that these actions are made of stainless steel. Thanks for that catch. Not being a steel guru, I didn't notice that error when I set it down here. I appreciate your watchfullness.

Perhaps this has something to do with your handle?

Unkel Gilbey

Alex Johnson
May 30, 2002, 09:50 AM
8620 is designed primarily for casehardening. It's nice to work with, machines like butter. As I recall the original mauser actions were casehardened anyway. There are probably superior materials to make actions out of, but a casehardened action has a lot going for it. Hard exterior, soft core, they are very strong and will take a lot of abuse unlike some through hardend steels that will shatter if improperly hardened. If your machining at home you would probably have better luck working on an easy machining alloy such as the 8620 rather than the more difficult to machine alloys like 4140 or god forbid stainless steels.

May 30, 2002, 11:37 PM
Personally , I like 4140 better than 8620.

Everything that I've read about 8620 reccomends using a heat treating furnace to heat treat. For the home bulider, that can be a pain.

On the other hand, for smaller gunparts 4140 can be successfully heat treated at home. It usually can be done at 1500 degrees and quenched in 150 degree oil. I wouldnt reccomend doing an action like this, that needs to be done in a controlled furnace. The receiver is not the place to be expeirimenting.

Harry Bonar
February 1, 2005, 07:26 PM
Dear Sir:
I've sought the answer to your question and I must say, I DON'T KNOW!!!!!

Harry Bonar
February 26, 2005, 10:44 AM
Dear Shooters:
This has eluded me for years; wouldnt it be great if we had reliable info about the analysis of German Steel used in their actions!
In many steel manuals, and many gun books and machinist manuals there is a "spark-test" shown - it is something I use in my shop constantly to identify High carbon steel (files etc) and cold rolled and carbide, grey and white cast iron, pickled and olied steel!
On Mauser bolts I have one a guy lost his cool with and bent the action he sheared off the lug area of the bolt!!! I tested the surface and it showed much carbon - however the internal steel (in the break) showed a medium carbon steel. Interesting! Very interesting!! I know the Germans, and virtually all Mauser builders PROBABLY worked from German prints, and specification sheets. Wouldn't we love to get our greasy little paws on a sheet like that!!
BUT, if you fit up a barrel so that you actually FEEL the bolt close on a LIVE ROUND, you can use a fairly "soft" action O.K.
Sorry to ramble on, and on, and on, and on! :D
I feel great about the smiths recommendation on 4130 and 4140 steel - it can be heat treated homogeneously clear through - makes laping lugs a joy!

February 26, 2005, 01:32 PM
The "4140 stainless " is an error !! 4140 is the preferred steel for receivers and that's usually what the factories use .It is commonly referred to as chrome -moly steel. It has to be heat treated. 8620 is case hardened and heat treated. 4340 is also an option . I would very carefully inspect ANY Mauser to see how well it's been case hardened [they used a fairly low carbon steel, case hardened] Many ,especially war time were very poorly done and if not redone may have bolt lug set back and other problems.Heat treating of the receiver must be done by someone who has experience doing it !!