Whether to heat treat a Martini extractor ?

[Jedman]

I have a Martini cadet rifle that was rebarred to 357 Maximum. The extractor that was in the gun looked as if was cut for a 30-30 sized rim so it was a little to loose fitting on the max case.
I made a new extractor from a bar of 4140 steel I had. I used a hacksaw, files, drill press, and milling machine to get it to the shape it is and it seems to work well. My question is, should I try to heat treat this part as the small fingers that actually do the extraction are very small and thin.
I dont have anything to use except a torch to heat the part with and quench it in oil ? and then temper it.

I dont want it to be brittle and break but would like to give it a little more strength and maybe springiness as you know sometimes you must use some force on the lever to pop a fired casing out of a Martini.

what do you all think is best ?

Thanks, Jedman172422172423

[JMtoolman]

Hi Jedman, my book on tool steels says to heat to 1500 to 1550 and quench in oil. Then draw the temper to 400 degrees. 1500 degrees is a yellow heat to the naked eye, just attach a soft iron wire through the hole and heat with a torch, plunge it into oil when it reaches the yellow heat. Then put it in your oven set at 400 degrees long enough to soak through the part and oil quench again. It's done! Motor oil is a fine quenching oil.

[jmorris]

Depends on your method and how hard/long it took you to make the part.

[Black Beard]

If you heat treat it there is a good chance it will distort on the first quenching. You need to ensure that those long fingers are plunged in to the oil at 90 degrees. Make sure you heat it for a long time in the oven to get a thorough temper. Don't bother with the second quenching. Just let it air cool.

Look up a heat colour chart to get a good idea of temperatures.

[Ballistics in Scotland]

I have a Martini cadet rifle that was rebarred to 357 Maximum. The extractor that was in the gun looked as if was cut for a 30-30 sized rim so it was a little to loose fitting on the max case.
I made a new extractor from a bar of 4140 steel I had. I used a hacksaw, files, drill press, and milling machine to get it to the shape it is and it seems to work well. My question is, should I try to heat treat this part as the small fingers that actually do the extraction are very small and thin.
I dont have anything to use except a torch to heat the part with and quench it in oil ? and then temper it.

I dont want it to be brittle and break but would like to give it a little more strength and maybe springiness as you know sometimes you must use some force on the lever to pop a fired casing out of a Martini.

what do you all think is best ?

Thanks, Jedman

I've been there and done it, though for a large Martini. The picture shows me part-way through removing everything that doesn't look like part of a Martini extractor. The first thing is, I think your extractor will work, but I think it would have been safer if you had removed a little less metal, particularly where it takes that stepup in width above the action frame. If necessary the inside top of the frame could be rounded to permit a radiused corner to the extractor.

I don't know just how much extractive effort a .357 Maximum requires, and especially yours, as chambers do vary. It would be unlikely to break off the little tabs if it was unhardened, but I think the limbs might twist, and eventually allow them to slip over the rim, or impede closure. Hardening isn't a difficult job. I would harden and quench, then cover it in something like engine oil in a shallow can, then set it alight with the torch. It should be adequately tempered when that burns away. It has always worked well for me with springs, and although more carbon than 4140 should be needed to make a good spring, the tempering process should work just as well.

[Ballistics in Scotland]

Hi Jedman, my book on tool steels says to heat to 1500 to 1550 and quench in oil. Then draw the temper to 400 degrees. 1500 degrees is a yellow heat to the naked eye, just attach a soft iron wire through the hole and heat with a torch, plunge it into oil when it reaches the yellow heat. Then put it in your oven set at 400 degrees long enough to soak through the part and oil quench again. It's done! Motor oil is a fine quenching oil.

No! Yellow heat is much too hot, and will very likely produce irreversible "burning" of a high carbon steel. The correct hardening temperature of about 1500ºF is achieved at the bright red which is often termed cherry red. 400ºF wouldn't do for an extractor either. That would produce the light straw colour which is good for extremely hard scrapers etc. for metal, which can be brittle. It is unsuitable for anything that has to endure flexure.

If you want to temper by colour (although I suggested what I think is a better way), you should aim for the attractive purple you get with about 540ºF. Anything with blue in it is unlikely to break or twist. It is a difficult shape to get the same colour all over, but heating in a bath of heated sand or pure tin should even it out. A bath of mineral salt is sometimes used, as you can see into it, but I don't believe anything you can use for other purposes, as you can tin, has the right melting point.

http://www.threeplanes.net/toolsteel.html

[Jedman]

For the tempering, Could I drop the extractor into a lead pot used for cast bullets ? A friend has one with a good temperature control and I would think it may work but the extractor would most likely float on the surface being it is a lighter metal.
Also I think I will polish it so it has smoother surfaces. The shape of the extractor is very close to the original and I didn't remove anymore metal than was required for it to have clearance.
The chamber on the rifle does seem snug as fired brass from it will not allow a jacketed .357 bullet to be inserted in the case mouth of the fired brass.

Jedman

[Ballistics in Scotland]

That would be an excellent way of doing it, as long as you hold it under. But it shares the disadvantage of sand, that you can't see the colours change unless you fish it out. Also the required temperature is lower than any alloy commonly used for casting bullets, and I doubt if it is worth making up a special one. I'd have modified the grip frame a little if necessary, and perhaps chiseled the extractor cuts in the frame larger with a tool made from a square toolbit, to permit putting more metal into the extractor. A lot of rounds now used in such rifles require a lot more extractive force than the .310 Cadet etc., let alone the .22 rimfire.

My extractor was in D-2 air hardening steel, although I am sure 4140 can end up just as good. O1 tool steel isn't usually classed as air hardening, but in thin sections it actually is, just enough to resist bending into shape, and this might be fine for this extractor. Tempilaq is another good method of indicating temperature. It is a lacquer which melts at a specific temperature, but it doesn't help you to heat something evenly.

I've got a thermostatically controlled electric kiln, of the type used in enameling jewellery etc. It is just about an inch and a half too small to attempt colour case-hardening of my Winchester 94 receiver, but perhaps that is just keeping me out of trouble. The bigger ones used for pottery and knifemaking, unfortunately, escalate dramatically in price.

[bigdog454]

Jed, you know that I have a small heat treat furnace.
BD

[Jedman]

bigdog,

No I didn't know you had a HT furnace, I will get with you soon as I have 2 of these extractors to HT as I rebarreled a large framed Martini and made a extractor for it also.
Maybe I can do both at the same time, Thanks for the help as I am sure you know much more about this process than I.

Jedman

[JFrench]

A heat treating oven would be the best choice. The part should be protected from scaling. Stainless foil or argon
purge. Heat treating by eye and by torch is affected by the available light in the heat treating room. Yellow is normally above 1700 degrees F in medium light conditions. Those are very small extractor hooks.

James

[Cap'n Morgan]

There's really no need for heat treating the part unless you are worried about wear on the fingers pushing the spent case. If force is needed to extract the case, something is wrong with the chamber or the load (a minimal force will push out six empties at the same time from a revolver) Should you experience a stuck case it's better to have the fingers bend slightly than breaking.