Type of steel for a Greener Martini extractor extension

[rickw55]

I have a Greener Martini action that I am going to re-barrel in .45-70. As part of the re-working process, I'll need to modify the extractor, which is designed for the special Martini shotgun shell. I plan to cut and fit and then weld a bar across the existing extractor in order to modify it to fit the .45-70 cartridge.
My question is what kind of steel to use for the extractor extension.Should I use a high-carbon steel (I have some W-2) or should I use a mild steel? Does it matter?
Thanks,
Rick

[country gent]

I think I would scrounge a piece of 4140 or similar, since your going to weld it pre hard wont be much benifit. Harden for around 40 rc when done. D2 would hold up nicely but is harder to machine. It is impact resistant though.

[Reg]

I may have to be corrected on this but I believe those extractors were mild steel, case hardened. If so I would worry about the junction ( weld ) of the two materials, generally the two different carbon levels don't like to mix and even with a full anneal, you might get a brittle joint.
I have done a good number of Martini extractors in the past, all were done with mild steel and then case hardened using either the old Herters powder or Casinite. All have held up well with no failures.

[Col4570]

Yes Mild Steel Case Hardened.

[rickw55]

Thanks for the advise. I appreciate it!
I think I will go with the mild steel and case-harden it. I do have some Kasenit.
Thanks,
Rick

[TCLouis]

Why not make the whole thing, may be easier than the welding mods

[Ballistics in Scotland]

It is
I may have to be corrected on this but I believe those extractors were mild steel, case hardened. If so I would worry about the junction ( weld ) of the two materials, generally the two different carbon levels don't like to mix and even with a full anneal, you might get a brittle joint.
I have done a good number of Martini extractors in the past, all were done with mild steel and then case hardened using either the old Herters powder or Casinite. All have held up well with no failures.

I think you are right, but the longer lobes to meet the .45-70 case head put more of a twisting moment on the arms of the extractor, and it is just possible that they may bend enough to let the tips spring off the rim. I believe I would silver solder the extensions using Brownells Silvalloy 355 in thin tape form. It is expensive, but a half ounce pack will last a long time on jobs like this. I would make the joint extend further down the extractor than the original lobes, and widen the slot in the barrel to fit.

I would use a high carbon steel, probably a bit of an old cabinet scraper I have cannibalized for other things. If I silver soldered I would also make up a tiny clamp from the same material and tiny screws, to keep it in place during hardening.

Here is some work done many years ago, not exactly on the GP shotgun, but on a very similar action which was sometimes used in the Birmingham trade for purpose-built rifles. The vulnerable stud to fix the position to which the barrel is screwed home, has been replace by a piece of high speed steel toolbit, silver soldered in place without affecting the hardness.

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[Ballistics in Scotland]

On reflection the best of all, if you are going to case-harden, would be to simply build up the existing extractor loves with weld, and shape them. The way the silver soldered lugs are shown in my bottom picture, they will be quite a bit stronger than the original ones. A radiused rather than 90 degree angle where they meet the vertical arms would also help. The reason the extractor lobes and their slots were so small on original Martini-Henrys was that they could be used with weaker balloon head or folded-head cases.

Do you have the chamber reamer? If you do intend to join in pieces of metal, the best way would be to make a complete ring, surrounding the head and rim, solder or weld it in, and then remove the unwanted portions. That will help with alignment.

[justashooter]

Agree with BS that silver soldering alloy steel is advised, but since we are talking mild steel, a weld build-up is good is surface hardened. this action was built almost entirely of 50-60 KSI mild steel. no need to apply 20th century technology to it.

[rickw55]

Thanks for the additional comments. I knew I would get some good advice!
I had considered silver-soldering in a piece. I was concerned about the strength of the joint, so I thought it might be better to weld it. But if silver-solder is strong enough, I may do that. I can do that myself, too, and shape the lugs as advised.
Ballistics, thanks for the pictures, too. They help a lot.
Rick