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Wow; good job; doing it the hard way. I usually weld them onto the existing bridge but you do get a new bolt race this way. Yes, your pics are way big.

Very nice. Out of my league.

"Armstrong" shaper

beyond me, but this looks amazing.

Nice . Do you have more pictures of the broach?

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With all that work why not just make a complete action. I love metal work but you are going way beyond fun for me! Very interesting project!!!

Great work. Keep the pictures coming.

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Good to see quality tig work. Not easy on some of the gun steels.

I recommend using a gas lens for the hard to reach places, but, from looking at your weld, your probably a better welder than me, and already knew about those!

Very very cool, I've never seen this done before. I'm unfamiliar with how the broach is used, is it pulled through? And what cartridge do you have in mind for the action? If I remember correctly, the original kurz mag box was something like 2.725", how long is the box going to be on your project? Thanks and I'll be following along closely

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I have found with some mauser receivers pre-heating around 350-400 works well to curb the porosity. I usually post heat as well, let them soak for about an hour, and shut the oven off allowing them to slowly cool.

Not sure it really helps, but, that is what my training tells me to do and it makes me feel better!

Once the porosity starts it can be hard to get rid of, especially in a tight corner where it is difficult to grind out. Frustration usually sets in big time. Tips you may or may not know to stop contamination of the weld zone-
- Hold post flow onto weld 5 sec. or so.
- Keep your filler rod in the post flow to stop it scaling, or snip the end off before every pass.
- If you don't have post flow then wire brush everything bright before every pass.
Good luck!!!

MORE! MORE! MORE!!!

yes this is very interesting.

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I had a similar issue with a customers 1909 receiver. I cut all the weld out, preheated to 400 and that seemed to help immensely.

VZ could be something else entirely.

Metallurgical analysis does not cost a great deal, I wonder, could we get a group together to pay for the cost of it and find a donor vz-24 to have analysed.

I don't know jack sh*t about this but...
As Italy paid CZ for their steel recipie to make the carcano out of, maybe a cheap way would be to test a carcano?

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A later model Carcano receiver is way tougher than any military Mauser.

I'd chip in for the sake of science.

I'll save you the time and destruction of an action.

I tested two VZ24's. One marked BRNO on the ring, the other with a Crest on the Ring. Neither was marked with a date, but due to the marking being different, I assume that they were made in different times. Are any marked with a date code?

3 checks per receiver, here are the ranges.

Carbon 0.37-0.41%, Manganese 1.38-1.45%, Phos 0.021-0.028%, Sulfur 0.026-0.034%, Silicon 0.50-0.54%. Nothing else interesting to report. Copper, chrome, nickel, moly were all less than 0.20%.

Each had a case depth of about 0.01" or so. I polished the side of the recoil lug to look at case depth.

I checked the rear ring on each after it was recontoured. The instrument is a Spectro Spectrotest. We use it at work for quick product checks. The recontoured area was checked to make sure I was getting a base metal reading with no influence from the added carbon in the case layer.

As to accuracy of the instrument, the carbon content is probably a little lower than it read by 0.005-0.008%, and the sulfur is probably lower as well. Carbon and sulfur are hard to analyze using a spectrometer, but it is close enough.

The carbon and manganese are the important elements, the silicon is used to deoxidize the steel (kill it), the phos and sulfur are residual from the open hearth furnace or cupola practice of the time. Feed stock would have been iron ore and those two elements come along for the ride. The rest of the elements are below any real effective level, though they could help a little.

Jeremy

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Very interesting Doug, I will ask some of the more knowledgeable welders and metallurgists at work if they know what specifically in the composition might be causing it.

Do you keep your interpass temperatures pretty low? From your pictures before it does not look like you are getting it really hot.

As a side note, could I purchase the tang from you? I have been looking for a tang that I can cut apart and measure the threads under a comparator.

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Any, update Doug?

Adam

Very interesting work and glad you have the time and skill to preform it.

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I work in refining and deal with a fair amount of welded carbon steel pipe though I am not a welder. It is not unusual to see BHN in the HAZ in excess of 300 after welding. We typically heat treat at 1150F or so to bring the BHN back down to 180 or so and to restore the lattice in the steel. It would be curious to see if PWHT addressed your issues.

What type of filler rod are you using?

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Doug,

Let me double check before I tell you incorrectly, but from *memory* I use ER80S-7? Or maybe D-2? Anyway, point being, I have run into this issue before with porosity welding up actions. My experiences were nowhere near as scientific as yours, (nor am I near the welder) but I found that as long as I was adding filler material to the puddle I did not have porosity issues. As soon as I stopped adding filler material and tried moving just the parent metal around I had bad porosity issues.

Similarly, I went though the variables assuming it was me. Welded on some 1018, 4140, and a few other misc pieces laying about with no issues.

I found after baking the action at ~400 deg for about an hour, then always feeding filler material whenever I formed a puddle solved the issue.

Now, all that being said, I did a square bridge on a 1908 Brazilian and never had an issue with multiple passes. 1909 Argentine I had a lot of issues.

The welding rod is usually a different composition than the parent material being weld. The reason is usually for strength, cracking,wetting and porosity. Examples would be welding aluminum. You don't use a rod made of 6061 to join 6061 togather. I have seen some stainless steel vacuum joins done without rod but they are usually a low stress joint. If the connection sees high stress a welding rod is always added in stainless.

There is a gentleman in the American Gunmakers who has done this type of work successfully before. His name is Stephen Heilmann. Maybe you could ask him what he does.