.

Imagine you bolt lugs were just one layer of Aluminum foil and hollow inside. [Of course hardened steel is two or three times stronger than Aluminum].

You could make enough bolt thrust with a cleaning rod and hammer to sheer off those lugs.

If the bolt lugs were solid Aluminum, the bolt might start to fail at SAAMI spec level handloads.

So it must be somewhere between the surface being .005" thick and .200" thick. I don't think it is linear relationship, as the skin is great in compression but out from the bolt body beam in bending, I believe the strength is a function of the height cubed. The material that is close to the bolt body would be in sheer, and that WOULD be a linear fraction of the strength ~ 2% of the strength from the skin.

AC and JonA are experts [they do it for a living] on the strength of metal shapes. Ask them.

InfoSponge,

The case would need to be around 1.5 mm thick (that is 0.060") before it began to be of significant aid in carrying load. However, even then it would only help slightly as the core still carries the majority of the load. To understand the concept best, you should perform stress / strength ratio calculation through the entire section of the action or lug. If you do so it will become immediately apparent that the CORE WILL ALWAYS CARRY THE VAST MAJORITY OF THE LOAD (LIKE BETTER THAN 95%) AND WILL ALWAYS BE THE INITIATION POINT OF FAILURE (PLASTIC DEFORMATION).

Also, most case carburized steels DO exhibit a very rapid transition zone from case to core. The reason is that the material doesn't possess sufficient carbon to form the necessary grain structure/composition without added carbon. Added carbon is provided during the carburizing process, which is time dependant with regard to depth of carbon enrichment. Typically, case carburized steels will not have case depth which are EVER greater than around 2 mm (0.08") to 2.5 mm (0.1") the reason is simply economic (it takes too darned long to bake that much carbon into the steel). Besides that you DO NOT need a case that deep as the CORE CARRIES THE LOAD!

Zach,

Believe me I AM RIGHT. The numbers published in the post by Alf, CLEARLY indicate that MOST of those actions will set back their lugs if loaded with ANY cartridged that produces significant thrust. Significant thrust would be anything loaded above ~ 40000 psi in a Mauser case head. This pressure threshold would be significantly less in the larger case heads.


Alf,

Depending upon what the material really is (I am still having a hard time believing the "actions get brittle at Rc30" part of the article you posted since this is typically the "sweet" spot for all steels with regard to balancing strength and ductility) reheat treatment would allow for a potentially significant improvement. The reheat treatment should be comprised of a new carburizing to obtain a case depth (carbon rich zone prior to quenching)of at least 0.02"(0.5mm) and then quench and tempering (to achieve the tempered martensite case which is desireable for wear resistance and that smooth as glass feel). Again the actual degree of improvement is material dependant. Of course if the materials are of medium to high carbon content case carburizing is not necesary, but then these material typically are not case hardened (at least not without the use of modern induction hardening equipment).

After my "discussion" with triggergard1 though, I have learned that the REAL reason that Mausers set their lugs back it that they utilize too small of a diameter bolt, that being a mere 0.700". The Mauser should have used 0.800".

Let the games continue.

ASS_CLOWN

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Alf,

Not saying that the article "made anything up" just saying that their findings are somewhat surprising, and causes me to wonder what some of those Mauser actions are really made of(or even heat treated for that matter).

I suspect that the commercial Mausers may have been made of better (read nickle steel or manganese steel) and received a "proper" heat treat. If you look through the data in your article some of the actions do have "proper" heat treatments (Mexican is a little too hard IMPO, the Vz24 ain't too bad, and there are a few K98 that look good too).
I would not want to use a "soft" (read less than Rc 20) Mauser action for a 505 Gibbs or 500 Jeffery, but that may just be me.

Don't get me wrong, I am not saying that Mausers are not good actions. At the same time, I think many (military actions now) had questionable material and/or heat treat specifications. I also feel that the statements regarding reheat treatment to obtain better material properties are well warranted. Particularly after review the data presented in the article you posted.

I am still stumped as to why a 0.800" diameter bolt is "really" necessary on any Mauser rifle, though.

ASS_CLOWN

At what point do the "B" & "C" scales overlap or relate to each other?

Ass Clown, if you've read that chart you'll notice very few if any had a core hardness approaching 25. That is the primary reason not to lap through the case. If they all had a harder core maybe, maybe you'd be right. But they don't and as usual you are talking out your ASS_CLOWN!

Try to visualize a thin hard surface supported by something that yields.



Yes, but all case depths are not the same, nor is there an abrupt transition from hard case to soft core. At what case depth does the the surface cease to be just a wear-resistant surface and instead begin to play a significant strength role of its own?

All,

So I take it building a .404 Jeffery on an Argentine M98 action is not the most suitable choice for a custom build out?

Maxman001,

From what I have read, and nothing more, I would say it would be wise to have the 1909 Argentina reheat treated to improve mechanical properties.

ASS_CLOWN

Thats the same conclusion I am coming to.
I am trying to do the economics on the process.
It might be better start with one of the new mauser type actions of Modern Manufactur or pick up a Ruger .375 and rebarrel it to .404.

Zach,

Actually, I would say YOU ARE THE IDIOT! Read the following sentence until you understand it, if you can.

CASE HARDENING IS FOR WEAR RESISTANCE NOT STRENGTH!! < !--color-->

Now this sentence.

CORE HARDNESS IS FOR STRENGTH! < !--color-->

If your Mauser is case hardened, but possesses a SOFT CORE ( WHICH IS A CONDITION THAT IS VERY EASY TO HAVE WITH THE LOW GRADE STEELS MOST MAUSERS ARE MADE OF < !--color--> ) you WILL GET SET BACK EVEN WITH YOUR ORIGINAL CASE HARDENING DEPTH! < !--color-->

Now if your Mauser has an adequate core hardness, something like Rc 25+, you will should not get ANY lug set-back IF you have 60%+ bearing contact between the lugs and their raceways! This WILL BE true EVEN IF THE CASE IS COMPLETELY GONE!!

ASS_CLOWN

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Alf,

Those mausers referenced in your article must have been made of some real crap steel (read low alloy or NO alloy) to get "brittle" at a measely Rc25. You wouldn't happen to know what these actions were made of? For the record, ALL steels get MORE brittle as they get harder.

I to enjoy these "discussions". Particularly the namecalling.

ASS_CLOWN

OK, what about the Persian mausers? 1917 Enfield actions?