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I decided to lap a barrel that was giving me fits with SBN treatment. I was mostly interested in the throat. I shot it today and it is finally behaving. My experience with 'Melonite' is that it is the proverbial double edged sword. Chad is right that you can't assume anything. The heat doesn't hurt the steel but that hard layer can sure play he!! on the bullets for a while.
I love the exterior finish but you get the bad with it. As far as whether to send a new barrel or seasoned one in, I think it can work either way. If you have an alligator skin looking throat, the SBN is just going to turn it into a rasp.
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I decided to lap a barrel that was giving me fits with SBN treatment. I was mostly interested in the throat. I shot it today and it is finally behaving. My experience with 'Melonite' is that it is the proverbial double edged sword. Chad is right that you can't assume anything. The heat doesn't hurt the steel but that hard layer can sure play he!! on the bullets for a while.
I love the exterior finish but you get the bad with it. As far as whether to send a new barrel or seasoned one in, I think it can work either way. If you have an alligator skin looking throat, the SBN is just going to turn it into a rasp. Yes, if you're going to send a barrel in for melonite/nitride, definitely make 100% certain the chamber and throat are exactly what you want first. It's a lot harder to fix minor details after nitriding. Even just simple things like minor burrs or roughness can be a problem when you give them a super hard surface treatment.
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I've got two custom actions that have been nitrided, the process seems to be the real deal as both of mine are perfect and the surface seems extremely durable. I don't have any barrels that have been done. One action is a Bighorn Origin and it's chrome moly, the other is a Kelbly Atlas Tactical and it's stainless. Both of mine were done by H&M metal processing of Akron OH. They seem to be the guys that the better custom action builders use 99% of the time so that tells me that they must know what they're doing. From the little reading I've done on the subject they seem to do their nitriding at a little reduced temperature on firearms parts to reduce the chance of warpage. They've developed their process geared towards firearms and the special considerations they require. I'd contact them for the straight scoop. Go to the mountain as they say if you want the real word. http://blacknitride.com/
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[/quote]
I have had 4 Defiance actions done. I called Glen and told him what I wanted to do. He told me to hold the Salt bath temp to 1050 or so. I have had great luck with CM actions. In fact, I haven't ever built on a SS action as I see nothing but upside to CM. Once they have been FCN treated, they seem to be much more corrosion resistant than 416 SS.[/quote]
Thanks good info.
"When you disarm the people, you commence to offend them and show that you distrust them either through cowardice or lack of confidence, and both of these opinions generate hatred." Niccolo Machiavelli
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Melonite. First, what is it?
That word is just a proprietary term for Salt Bath Nitride. Something that has been around for years. In the gun world this really took off around 10 or so years ago when guys started having barrels "cooked" so that they'd last longer. Mixed results were the general consensus. The big reason is, you have to be very careful in how you do it. "SBN" effectively brings the shell hardness level of a barrel into the 50-60 Rockwell range. That's great for a bore as it'll just wear longer. The issue however can be the throat. You would want to run a couple hundred rounds down the bore before sending it off. Failure to do so can result in a barrel that just takes a very long time to settle down.
So, that covers the ghist of that stuff.
Onto receivers:
People want this in the hopes it'll make a bolt run smoother. I get that. However, you really, really, need to take a long and hard look at what you are doing to the basic chemistry of the steel. It matters.
For instance: An action made from 416R stainless will typically heat treat to around 42-44 Rockwell C scale. This is done around 1500-1600 Degrees. It's an air quench material. So, you get it hot, soak it at that temp for awhile, then quench it by blowing an inert gas, like nitrogen over it, so that you don't suffer any oxidation ( or hydrogen embrittlement ). Then your done. A lot of aftermarket action companies like this stuff because you can machine it easily after heat treat and it doesn't tend to move around and distort a whole lot. Great for the bottom line because tooling costs and machine requirements don't go through the roof, and you can finish the parts and be done with them. Easy and that keeps costs in at a level folks can live with.
If done right, conventional heat treatment will get the hardness to penetrate all the way through the material. Very good as hardness directly correlates to ultimate tensile strength, toughness, etc. All things an action requires.
Now, go cook it in some ammonia based salt at around 900-1000 degrees Fahrenheit. The surface hardness will increase to around 50 or 60 rockwell C scale. This is great, but...(always a but) WHAT did it do to the core's hardness and tensile strength? 416R anneals at around 1100 degrees. Annealing removes hardness. Your within 100 degrees of that temperature. Don't fool yourself into thinking it wont influence the final outcome. Steel is not an "on/off" switch. The chemistry of the material fluctuates just like it does in a loaf of bread, so how it behaves changes as well.
Using 416R SS as the example, its chemistry is rather complex when compared to something like chromoly. The way you approach these two is quite a bit different and that really needs to be respected.
With 416R, you essentially make a hard boiled egg. Hard shell, with material that runs the risk of being softer inside and losing tensile strength.
My point here NOT to say this happens with all actions, but make no mistake, it does happen with some and its solely based on the material that the receiver is made from. You really, really want to know the exact steel composition. Failure to do so might get you an action that essentially becomes a time bomb with a very unpredictable timer...
You sneeze a case by over pressuring it or having some sort of just worst case scenario event, you may just go on with your life, or you could very well end up picking gun parts out of your face.
Having done that once, I don't recommend it.
Know exactly what you are asking for and make sure the folks doing it know as well. ASSUME NOTHING.
Chad, Given your explanation above, what are your thoughts on the Bighorn Origin? John
If my people, who are called by my name, will humble themselves and pray and seek my face and turn from their wicked ways, then I will hear from heaven, and I will forgive their sin and will heal their land. 2 Chronicles 7:14
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Melonite. First, what is it?
That word is just a proprietary term for Salt Bath Nitride. Something that has been around for years. In the gun world this really took off around 10 or so years ago when guys started having barrels "cooked" so that they'd last longer. Mixed results were the general consensus. The big reason is, you have to be very careful in how you do it. "SBN" effectively brings the shell hardness level of a barrel into the 50-60 Rockwell range. That's great for a bore as it'll just wear longer. The issue however can be the throat. You would want to run a couple hundred rounds down the bore before sending it off. Failure to do so can result in a barrel that just takes a very long time to settle down.
So, that covers the ghist of that stuff.
Onto receivers:
People want this in the hopes it'll make a bolt run smoother. I get that. However, you really, really, need to take a long and hard look at what you are doing to the basic chemistry of the steel. It matters.
For instance: An action made from 416R stainless will typically heat treat to around 42-44 Rockwell C scale. This is done around 1500-1600 Degrees. It's an air quench material. So, you get it hot, soak it at that temp for awhile, then quench it by blowing an inert gas, like nitrogen over it, so that you don't suffer any oxidation ( or hydrogen embrittlement ). Then your done. A lot of aftermarket action companies like this stuff because you can machine it easily after heat treat and it doesn't tend to move around and distort a whole lot. Great for the bottom line because tooling costs and machine requirements don't go through the roof, and you can finish the parts and be done with them. Easy and that keeps costs in at a level folks can live with.
If done right, conventional heat treatment will get the hardness to penetrate all the way through the material. Very good as hardness directly correlates to ultimate tensile strength, toughness, etc. All things an action requires.
Now, go cook it in some ammonia based salt at around 900-1000 degrees Fahrenheit. The surface hardness will increase to around 50 or 60 rockwell C scale. This is great, but...(always a but) WHAT did it do to the core's hardness and tensile strength? 416R anneals at around 1100 degrees. Annealing removes hardness. Your within 100 degrees of that temperature. Don't fool yourself into thinking it wont influence the final outcome. Steel is not an "on/off" switch. The chemistry of the material fluctuates just like it does in a loaf of bread, so how it behaves changes as well.
Using 416R SS as the example, its chemistry is rather complex when compared to something like chromoly. The way you approach these two is quite a bit different and that really needs to be respected.
With 416R, you essentially make a hard boiled egg. Hard shell, with material that runs the risk of being softer inside and losing tensile strength.
My point here NOT to say this happens with all actions, but make no mistake, it does happen with some and its solely based on the material that the receiver is made from. You really, really want to know the exact steel composition. Failure to do so might get you an action that essentially becomes a time bomb with a very unpredictable timer...
You sneeze a case by over pressuring it or having some sort of just worst case scenario event, you may just go on with your life, or you could very well end up picking gun parts out of your face.
Having done that once, I don't recommend it.
Know exactly what you are asking for and make sure the folks doing it know as well. ASSUME NOTHING.
That’s a helluva thorough reply Chad, glad to see someone with your expertise posting here
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That’s a helluva thorough reply Chad, glad to see someone with your expertise posting here
It would've been a lot better if he could back it up with accurate facts. As it is, the real numbers show that a lot of what he said doesn't hold water. It's not "expertise" when it's wrong...
Last edited by Yondering; 12/06/18.
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That’s a helluva thorough reply Chad, glad to see someone with your expertise posting here
It would've been a lot better if he could back it up with accurate facts. As it is, the real numbers show that a lot of what he said doesn't hold water. It's not "expertise" when it's wrong... Plus 4x
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That’s a helluva thorough reply Chad, glad to see someone with your expertise posting here
It would've been a lot better if he could back it up with accurate facts. As it is, the real numbers show that a lot of what he said doesn't hold water. It's not "expertise" when it's wrong... To be honest, i hadn’t read this entire thread and seen the dissenting opinions on SBN treating actions when I made that reply. I know very little about the subject, or metallurgy in general, so I have no basis to agree or disagree with you or with Mr Dixon, didn’t mean to imply so But it does seem to me Chad is an accomplished riflesmith and machinist so I will certainly listen when he’s talking.
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Email from a military armor
You may find this interesting, see e-mail below.
I was the Armorer for the Army Reserve Shooting Team for over a decade so I do have quite a bit of experience with both processes.
As I am sure you know, most G.I. barrels are made from chrome molly steel which is more susceptible to corrosion than stainless steel. Chrome lining is used on G.I. bores both to extend their shooting life and to protect them from corrosion that can be a problem in battlefield conditions where maintenance is sometimes sporadic or insufficient. Chrome lining does a pretty good job of protecting battlefield weapons. One of the objections to chrome lining is that it is thought to decrease accuracy. This seems to be a valid criticism and is backed up by machine rest tests I have conducted of identical barrels (same manufacturer but half chrome lined and half not).
As you are aware most barrel "wear" is in the throat area. So eventually the hot gasses from the burning of the gunpowder will eat thru the chrome lining at the throat. It is rumored that at this point accuracy will plummet but I have not found that to be true. (Or if true, it is overstated or maybe only occurs for that short period when there is both chrome and bare steel in the throat simultaneously - just at the point of initial break thru.) Chrome lined barrels can continue to shoot well for thousands of rounds after the bare barrel steel at the back of the barrel (throat) has been exposed due to erosion of the chrome lining. Another criticism of chrome lining is that it can flake off later in the life of the barrel resulting in poor accuracy. Obviously, this could also cause maintenance problems if the user is depending on the chrome to ward off corrosion and thus is careless in his bore cleaning. If corrosion is allowed to occur pitting will result and that will ruin accuracy for sure.
Barrel pitting was one of the reasons I got involved in Salt Bath Nitriding. I was loosing nearly as many expensive match grade barrels to improper maintenance (causing pitting) as I was to wear out. This was under the relatively benign target shooting conditions. Obviously given the reputation of degraded accuracy, using chrome lining wasn't an option. So for the past couple of years I have been Salt Bath Nitriding all of my match barrels and haven't had a single one exhibit any pitting. During that 2 yr. period shooters have put anywhere from a few hundred rounds to thousands of rounds on said barrels. I don't know how long the coating will persist so at this point I am still evaluating it as a preservative. I don't know what will happen in another year or two when these barrels get more wear on them. Salt Bath Nitriding goes on both inside of the bore and on the outside surface. So, instead of 2 manufacturing steps you have combined them into one. Salt Bath Nitriding doesn't degrade accuracy one iota, unlike chrome lining. This was the first thing that I verified when I began using the process. I broke in a bunch of barrels and then machine rest tested them for group. I recorded and kept the targets, cleaned up the barrels, and sent them to MMi TruTec for the Isonite process. When they came back I reassembled them on the same receivers with the same torque settings, same bolt carrier assemblies, same flash suppressors, etc. Then they were retested with the same ammo lots. NO degradation in accuracy and about a 1% increase in muzzle velocity.
Chrome lined barrels seem to clean up rather easily after a range session. I found the ease of cleaning of Isonite coated barrels to be similar to chrome lined barrels. The Isonite barrels clean up the easiest of any non chrome lined barrels I have ever used. Isonite can be applied to either stainless or chrome molly but the factory needs to know what steel you are sending them because the application process varies a bit. Again, I only have about 2 yr. of cleaning experience with Salt Bath Nitrided barrels. I don't know if the ease of cleaning will continue as the barrels get more rounds on them. Generally speaking, most non coated barrels get harder to clean later in life. Although stainless has a reputation of being corrosion resistant it isn't corrosion proof (I have had plenty of them return pitted) so I coat both my C.M. and my SS barrels. The Isonite on the outside of the stainless barrels cuts reflection down so my shooters like it.
I mentioned flaking of chrome lining inside the bore. Joel Kendrick is my contact at MMi TruTec, the company in Arkansas that does my Salt Bath Nitriding (they call it Isonite). He was mentioning using the Salt Bath Nitriding inside the bore prior to chrome lining it to get a better adhesion. He is currently working with one of the military contractors (maybe F.N., but don't quote me on that) relative to this process. He has given me permission to give out his contact information so I have cc'd him in my reply to you. He can give you the specifics of any testing and evaluation that has been done relative to this process and can give you quotes, etc. should you just be interested in the Isonite by itself as I use it.
One last quick note on chrome lining. Such barrels have the reputation of changing point of impact when heated up. I have found this to be very true. It may be due to the way the different metals (chrome molly and chrome) expand inside the bore. What ever the reason, it does happen and, again, this was verified on a state of the art machine rest. Isonite doesn't exhibit this characteristic.
I am sure you are well aware of some of the things I covered. Lacking specific questions, I just sort of used a shotgun approach which ended up being fairly long. If I left anything unanswered please feel free to get back to me. I have enabled my Spam Blocker to allow your e-mails to come in with out the automated hate responses that Earth Link sends out. I am sure Joel would also be glad to clarify the technical aspects of the Salt Bath Nitriding process. So far I am very pleased with it.
Best of luck!
Joel Kendrick is a long time friend and fellow BR shooter. Joel does both short range and long range shooting is his passion. Joel was an engineer for a company in NC that made gas struts for trunk, hood, and other lifting purposes. They used melonite on their shafts. Joel thought I will come in at night and do a couple barrels. It worked very well for him. Joel did a few for me early on and I was real pleased. Most PPC BR barrels are replaced in the 1000-1200 round range. They were not inaccurate at that stage, but .020" extra spread will lose the match. My first was a Kreiger and after 5000 rounds it still shot very well and borescoped like almost new. Joel was hired by Mimi Trutech to head up their rifle barrel work. He is doing so well that I can't get any done for myself anymore.
Last edited by butchlambert1; 12/07/18.
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That’s a helluva thorough reply Chad, glad to see someone with your expertise posting here
It would've been a lot better if he could back it up with accurate facts. As it is, the real numbers show that a lot of what he said doesn't hold water. It's not "expertise" when it's wrong... To be honest, i hadn’t read this entire thread and seen the dissenting opinions on SBN treating actions when I made that reply. I know very little about the subject, or metallurgy in general, so I have no basis to agree or disagree with you or with Mr Dixon, didn’t mean to imply so But it does seem to me Chad is an accomplished riflesmith and machinist so I will certainly listen when he’s talking. I included a link in my first reply that lists temperatures pertinent to 416 stainless. They clearly show that Mr. Dixon's numbers are so far wrong that the point he's making doesn't hold up. I don't have any personal beef with Mr. Dixon, but if someone is going to present themselves as an expert and offer advice, I'd sure rather that advice be limited to things they actually know.
Last edited by Yondering; 12/07/18.
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