Friday, March 18, 2022

Plantars Fascitis and Springfield M-1903 heat-treatment

 

Well, that is embarrassing. Especially after talking bravely about donning a 40 pound pack and doing a walk-about.

The last time I had a debilitating bout of plantars fascitis is when I first started running in 2004. I ramped up too fast. I tried orthodics with marginal success. The key was to take a break from running and religiously stretching my calf muscles.

After hardening up (and switching running shoes) I could mostly stop stretching.

This bout of PF is in my right foot and seems to have been triggered by standing on a ladder and hauling water across the pasture.

Bummer!

Springfield Model of 1903


 

I am trying to make sense of what the talking-heads in various videos and essays are saying about issues with early-number, Springfield Model of 1903.

A small fraction of the early-number M1903 had receivers that exhibited brittle failures when firing production ammo. Brittle failures are less desirable than ductile failures because ductile failures at least partially contain the energy while brittle failures do not.

They talk about furnaces being too hot, contaminants segregating, metal too brittle, two-part heat-treatment rather than one-part heat-treatment and so on. As somebody who has a little bit of formal training in metallurgy, the vague explanations are more confusing than enlightening.

My best guess at this point is that the low-number receivers were case-hardened at a higher temperature than the process specified. Instead of a thin, hard, wear-resistant outer surface over a ductile core, entire sections were the hard material (aka, martensite).

An often overlooked feature in properly case-hardened parts is that the thin, hard, brittle material on the surface is under compression because martensite crystals are less densely packed than non-martensite. That compression helps stop crack-growth.

The carbon in case-hardening diffuses into the material. The hotter the process, the more quickly the carbon diffuses and the more quickly the thickness of the grows.

A possibility that does not get discussed is that some parts might have not been properly segregated and might have gone through the case-hardening step several times. That is, case-hardened parts might have been misplaced into the wrong bins after spilling on the floor and thus received double (or conceivably more than two if they were "Christine") trips through the carborizing process.

A part that was case-hardened at too high of a temperature could conceivably have no ductile core in the thinner sections and no (or very little) residual compressive stresses. One fix would be to anneal, re-quench and then temper at 900F-to-1200F. Not a great solution but one that would reduce the likelihood of your M-1903 turning into a grenade.

It is worth noting that nearly all modern firearms are made of medium-low to medium carbon steel. I suspect that some of them are machined from prehardened steel since carbide cutting tools don't have a problem with it and there is no dimensional distortion introduced by heat-treatment after machining.

The two-part heat-treatment, I am guessing, involves allowing the case-hardened parts to cool to approximately room temperature before reheating and quenching rather than simply dumping them from the case-hardening oven into the quenching bath.

An alternative (a little mind-boggling) is that "two-part" referred to tempering the quenched parts rather than using them "as-quenched". I cannot fathom using quenched, untempered, steel parts but maybe it was a thing back-in-the-day.

Does anybody KNOW? Ambiguous explanations bug me.

6 comments:

  1. Dennis from Poland here, Mr. ERJ.
    There is a great book for shooting historians called Hatcher's Notebook. I think he was part of the investigation into the receiver failures. It is a good book

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  2. What little I've read is just like you mentioned. It confusing, and like any safety issue the .gov sees, they threw the baby out, too. In the ensuing years the information became myth and conjecture.

    Kind of like the M-16 morphing from a deadly, dependable weapon when fielded by the Air Force in the early 60's to a problem after the .mil go done imposing their changes on it.

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  3. There really is a simple solution to all this. Use a Mauser action and never look back

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  4. dr. scholl's pf insoles worked for me, along w/ the exercises. my p/a told no matter what avoid the surgery. she said use frozen coke bottles, roll them under your foot. it works, along with those step exercises where you stand on the edge of the step and lower your heels below horizontal.

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    Replies
    1. i built an 03a3 from parts. from what i can glean as long as you stick to regular ammo you'll be okay, no magnum plus "p" extended range yada yada rounds. part of the issue was bolt heads and since there's no way of telling which had you got...

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  5. That sight looks just like one I have on a 1952 Winchester model 71.

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