Barrel steel, beyond stainless

[allen529]

I saw Boots Obermeyer's name in an earlier post. His SS barrels were not 416 but C4. He had one supplier from what I was told. I have two of his barrels and they both were marked C4.

Personally I like 17-4 but I do not think its as practical a metal for barrels cost wise.

 

[davidjoe]

I received a 1.5” round of tungsten carbide today that is six inches long. The material is quite expensive, several hundred dollars at this size.

As I understand tungsten carbide, it’s compressed from powdered Tungsten and cobalt.

Does it appear that the piece I received was actually formed around an existing piece of the similar material from looking at this picture?

On one end, I see the outline of a preexisting round, which itself looks hollow.

On the other end, I don’t see that.

Now, I have sunk bricks into poured, wet cement to stretch a single load for my own outdoor kitchen’s foundation, which is not something I’d smile at a contractor for doing if one had been paid to get it perfect, but is it practice to recycle odds and ends of caribe this way, or is what I’m seeing not that at all, but rather possibly the imprint of a stop piece in an industry standard cutting tool?







On the bottom picture, I don’t see an outline, though clearly it was not cut by the same tool and possibly there is one, I just can’t see it.

 

[cosmic creepers]

So, I've wondered about this very question - a lot.
On Lija's website, they say that CM is more resistant to abrasion and SS is more resistant to heat erosion.
They don't say, but my understanding is there is no difference in inherent accuracy between the two metals. Apparently SS can be machined more precisely => better chance of being more accurate.

I wonder if there is any study on surface hardness/lubricity if the two metals.

I have both ChromeMoly barrels and stainless barrels in some of the same and some different calibers.

While my experience is incredibly subjective, and also due to the fact that my chromemoly barrels were hand made by a barrel craftsman, and rifled with a button made to exacting tolerances, and my stainless barrels are off the line "match" barrels.

My experience is that the chromemoly barrels are brighter, have crisper rifling, are mirror polished, smoother to clean, easier to clean cleans in less strokes and patches, and all of my guns are as accurate as their barrels or loads allow.

Not sure about the heat erosion thing. I have heat cracks in my stainless barrels and my cm barrels, but my cm barrels don't copper as much.

Might be the high quality button. Might be the high quality craftsman, might be the high quality steel, Might be the lubricity coefficient of the steel. Might be a combination of the above

I'd love to know.

 

[ronemus]

My next barrel is on order and it will be Bartlein's new BBmod400 stainless - it's a bit harder than regular 416R, although it's similar in composition. Barrel life is supposed to be doubled at a moderate increase in price. It will be a while before I know because Bartlein orders are 10 months to 2 years out. This on is for my spacegun and will be smithed by John Holliger; he had no reservations about it except the wait time.

BBmod400 is a proprietary material so I don't know the actual composition. I suspect they tweak some minor additives and may add dome unusual ones. That requires buying an entire melt from the supplier (at least 4000 pounds) - that's a lot of barrels! If I still had access to chemical analysis equipment (a scanning electron microscope with EDS would be perfect) but not the sort of thing you'll find in my garage after retiring.

 

[ronemus]

There are examples of this concept (using a different material insert for the throat) in heavy weapon gun barrels, but they are not carbide. Not cheap to do and much more expensive than making them from a single material.

You're probably thinking of Stellite. From the wikipedia article: "The first third of the M2HB machine gun and M60 machine gun barrels (starting from the chamber) are lined with a Stellite alloy." I worked for Union Carbide for a time and never realized that they owned the patent on it, and produced a variety of compositions for different purposes.

 

[ScottMcc]

I posted on here a few years ago, thinking out loud about barrel steels. I personally am drawn to stainless barrels for target rifles, but it has drawbacks too. We know that rapid fire causes more damage to the throat as the steel gets hotter, so I was wondering about the thermal conductivity of the various alloys of steel. The faster the heat could be drawn away from the throat, the faster it will cool and the less damage will happen from the next shot. This is a weakness of stainless. The thermal conductivity of stainless is far less than carbon steel. I don't have my engineering textbooks handy, but it is a small fraction, like 10 or 20 percent as much (btu per inch per degree F). It's practically a thermal insulator.

So I wonder if a stainless could be developed specifically with gun barrel properties but also enhanced thermal conductivity. It might mean less nickel or chromium, or more of something else. Unfortunately the most conductive materials are soft, like silver and copper. Who knows? Maybe the perfect material was developed years ago for some other reason?

I'm going to look for my old thread. The comments then were pretty hostile..

 

[ScottMcc]

Here's my old thread, 11 years ago. And the conductivity of stainless is about 75% LESS than carbon. Is it a factor? Maybe. Definitely maybe.

What steel alloy for barrels?

Most custom barrels are stainless right? Stainless machines better and I heard holds up to throat erosion better, but stainless has a very low thermal conductivity number. It seems to me that with rapid firing, heat will not spread away from the throat area as fast with stainless, maybe...

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