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EROSION

Webster

https://www.stainlessshapes.net/416r-stainless-steel-gun-barrel/
Machinability – Material has been stress relived and straighten to guarantee good machinability for gun drilling and reaming, which is necessary to maintain bore accuracy. The microstructure responds to heat treating which gives this material a uniform core hardness along the length of the bar. The material is heat treated to HRC 26 -32 available special HRC requirements can be met upon request.

After reading the literature put out by several gun barrel suppliers it appears that the spec that barrel makers have is related to the ability to machine a deep hole that is exceptionally straight and holds dimensions well. Not related to erosion.

Barrel erosion is called hot gas erosion. It is not related to the hardness or slight variation in composition of alloy content. The erosion is related to the melting temp of the steel (which should not be a variable, the temp and volume going done the barrel. There are charts that have been on this website that show the relationship of powder charge, bore diameter and how cartridges rate for barrel life.
 
Mikecr has that spreadsheet.
Some groups believe longer bearing surface has a significant impact.
Some believe boat tails are worse than flat base.
Some believe it's the amount of powder rather than longer bearing surface.
Some the believe powder heat of explosion has a very significant impact.
 
Webster,
Erosion isn't going to change much between varieties of 416 since the metalurgy is about the same. I wouldn't expect heat treat to affect erosion because the surface is heat treated by the hot gases.

I haven't done much research on hot gas erosion but I have looked at mechanical wear (different applications over the years, not related to gunsmithing) and 17-4ph is very resistent to mechanical wear. I don't know if that would transfer to barrel erosion or not but I've often wondered how much research has been done on other wear resistant steels for gun barrels, especially 17-4ph.

--Jerry
 
carlsbad said:
Webster,
Erosion isn't going to change much between varieties of 416 since the metalurgy is about the same. I wouldn't expect heat treat to affect erosion because the surface is heat treated by the hot gases.

I haven't done much research on hot gas erosion but I have looked at mechanical wear (different applications over the years, not related to gunsmithing) and 17-4ph is very resistent to mechanical wear. I don't know if that would transfer to barrel erosion or not but I've often wondered how much research has been done on other wear resistant steels for gun barrels, especially 17-4ph.

--Jerry
Click to expand...


Jerry, Lother Walther has a barrel that I think may be very similar to 17-4. They call it LW50. Lot of smiths will not chamber it.
 
butchlambert said:
What is this thread about?
Click to expand...

Guys have been talking about how fussy barrel maker companies are about the steel specs when they buy bar stock. I just wanted to point out that the spec must be related to the ability to drill a long straight hole and hold dimensions. Nothing else implied. Replies are already wandering.
 
Webster said:
https://www.stainlessshapes.net/416r-stainless-steel-gun-barrel/
Machinability – Material has been stress relived and straighten to guarantee good machinability for gun drilling and reaming, which is necessary to maintain bore accuracy. The microstructure responds to heat treating which gives this material a uniform core hardness along the length of the bar. The material is heat treated to HRC 26 -32 available special HRC requirements can be met upon request.



After reading the literature put out by several gun barrel suppliers it appears that the spec that barrel makers have is related to the ability to machine a deep hole that is exceptionally straight and holds dimensions well. Not related to erosion.

Barrel erosion is called hot gas erosion. It is not related to the hardness or slight variation in composition of alloy content. The erosion is related to the melting temp of the steel (which should not be a variable, the temp and volume going done the barrel. There are charts that have been on this website that show the relationship of powder charge, bore diameter and how cartridges rate for barrel life.
Click to expand...

I could be wrong, but I doubt the 26-32RC is the hardness that they desire.
 
Last edited:
Webster said:
Guys have been talking about how fussy barrel maker companies are about the steel specs when they buy bar stock. I just wanted to point out that the spec must be related to the ability to drill a long straight hole and hold dimensions. Nothing else implied. Replies are already wandering.
Click to expand...

Without the ability to drill a long straight hole, nothing else matters. If you don't start out with accuracy, then who cares about erosion.

But my original response did address the issue, although perhaps subtly so I'll spell it out. When the barrel manufacturer picks the alloy, that sets the erosion characteristics. Other portions of the spec such as heat tread (hardness), ECT results, homogeneity, etc are more about machinability that erosion resistance.

--Jerry
 
butchlambert said:
Jerry, Lother Walther has a barrel that I think may be very similar to 17-4. They call it LW50. Lot of smiths will not chamber it.
Click to expand...

Butch,
Can't find anything about it on their website. Like I said in another reply, without accuracy, who cares about erosion resistance so I haven't much experience with Lothar Walthar. Years ago I chambered a Grendel for a guy on an LW blank he provided and it wasn't a success.

I've chambered some pretty hard die material including varieties of 17-4 PH so with proper care, I'm sure it can be chambered.

--Jerry
 
I bet Bartlein will do you a barrel for you. I also bet you will change your mind when they quote you the price. I have machined a lot of it and would include the cost of a new reamer in each chamber you want me to do.
 
carlsbad said:
Butch,
Can't find anything about it on their website. Like I said in another reply, without accuracy, who cares about erosion resistance so I haven't much experience with Lothar Walthar. Years ago I chambered a Grendel for a guy on an LW blank he provided and it wasn't a success.

I've chambered some pretty hard die material including varieties of 17-4 PH so with proper care, I'm sure it can be chambered.

--Jerry
Click to expand...


Jerry, it needs a lot of feed and speed. The ones I chambered had quite a difference in bore size from barrel to barrel. A solid carbide reamer is a big help.
 
carlsbad said:
Without the ability to drill a long straight hole, nothing else matters. If you don't start out with accuracy, then who cares about erosion.

But my original response did address the issue, although perhaps subtly so I'll spell it out. When the barrel manufacturer picks the alloy, that sets the erosion characteristics. Other portions of the spec such as heat tread (hardness), ECT results, homogeneity, etc are more about machinability that erosion resistance.

--Jerry
Click to expand...
Don't know what you mean by the barrel maker picks an alloy. I believe all comp barrels are 416 SS. 95% of carbon steel barrels are probably the same alloy
 
There's a lot more to it than just melting point. There are chemical reactions, mechanical abrasion, flame temperature, heat capacity/conductivity of the barrel material, bullet obturation, how well the material maintains hardness at high temperature, barrel time, and phase changes in a thin layer of the bore exposed to the flame. There are probably more factors. It's really complicated. There are materials that have substantially better wear characteristics than steel. They're also expensive or hard to work with - stuff like Inconel, U700, Stellite, etc.

One interesting thing I've learned is that fire cracking is due to the phase change in the exposed steel. That basically means that the arrangment of the metal atoms is changed, which will alter the volume occupied by those atoms slightly. Those volume changes are what cause the cracking. Not terribly useful information, but I thought it was neat.
 
Apparently Crucible Industries is still in business -

rogina said:
I wish Crucible steel was still being made.
Click to expand...

They answered my call. Site is valid. 416R stainless is still being supplied by Crucible steel LLC and many others for a wide variety of uses including rifle barrels.

rogina's uncertainty should be dispelled & Butch's comment ("No") as to the propriety question affirms what we all knew. Butch's like of rogina's comment as to the availability of "Crucible steel" caused me to take a look at Crucible Industries LLC.
 
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