Home Forums Hunting & Shooting Custom Rifles & Wildcats Melonite?

Is Melonite a good treatment for a custom rifle?

It might be ok for a fiberglass stocked rifle IMHO. I would prefer a nice rust blued finish on anything with really good wood on it

I can't completely agree on that. This is a 40X that I built and it has a special SS barrel, so Melonite it is.



These photos do not do it credit.
I would do as Oldelkhunter stated if the barrel wasn't special.
Melonite greatly increases barrel life.

The rifle won't be fancy wood, and I am considering it for the added barrel life.

But I think it looks great on your rifle Butch.

Thanks!

how does it add to barrel life?

Melonite is a trade name for salt bath nitriding.

It forms a hardened case on all surfaces exposed to the salt bath including the bore.

OK, gotcha. Good to see you back around here, Burnsy.

Thanks Don.

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.

Thanks for the great explanation Chad.

I sent you a PM with a couple specific questions.

Some of what you said in that post is good, but some of it is not, and your basic premise about what nitriding does to the core material displays poor understanding of heat treatment. Nitriding brings the core material into the tempering ranges (sometimes at the high end, depending on the steel) but absolutely does not approach annealing temps.

Your numbers about 416 stainless are all wrong. It is not annealed at 1100 degrees, annealing is done at much higher temperature, around 1600 F. Hardened 416 can be tempered up to 1400 F, well above nitriding temperature.

Here is spec sheet from North American Stainless about 416 steel. Note the caution about tempering between 750-1075 F, which may be what you were thinking of but is very different than what you said. Relevant bits start partway down page 1:
https://www.northamericanstainless.com/wp-content/uploads/2010/10/Grade-416.pdf

I guess Bat machine doesn't know about metal. They Melonite some of their receivers if you want.
I have found that it is much better to send a new barrel than one that has had a lot of rounds through it.

Listen to Yondering. I've had many barrels and a few bolt bodies done. I highly recommend it, just use a reputable firm.

I've had mixed luck with barrels. I wouldn't do one again myself. I only buy CM actions and I have them done and it is a great treatment for such. I have had NO rust on any of them that I have had done.

I have put my Glocks through hell with nary a trace of rust. I suspect that Salt bath nitride on a barrel could be fine but I think you need to have it perfect before you treat it and I have had 2 brand new barrels that didn't shoot very good after being treated. My guess is to break in the throat very thoroughly first and then clean the dickens out of it before sending it off. I'm not willing to spend $600 again to try.

Last I checked, BAT Machine does not use 416R. They are using 15-5PH and/or 17-4. Vastly different materials. Apples and onions...

LOL.

15-5 is more likely to have it's condition altered by SBN than 416R.

15-5 @ Condition H900 or Condition A is going to be Condition H1025 after conventional SBN.

Not saying there is anything wrong with SBN 15-5, just saying that one needs to understand what Condition is the desired finale product.

SBN on 416R is a simpler as noted above the temps involved won't change the heat treat of 416R.

With chrome moly actions is there any concern on hardness? The WWII era Mauser's were left soft and then case hardened with the idea that the action would be tougher than if hardened completely through. The only issues I know of are when a Mauser is surface ground and not re-heat treated.

Ask Mr Dixon, he has all the answers.

Good to see you posting again John.

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.

I have zero experience with melonite on barrels. I have used it extensively for rust prevention in food plants. Most of our equipment is 304 or 316 stainless, but certain applications won’t allow stainless. We then use melonited carbon steel. Washdown of equipment involves a lot of water, a lot of caustic. And a lot of acid. Just an ordinary carbon steel part will rust in minutes after a cleanup. A painted motor might last a month. Epoxy coated longer, but rust will still come. Melonited parts simply do not rust in our application.