Melonite barrel treatment

[Trickymissfit]

How does the extra hard alloy used in the Lothar Walther barrels work compared to this mar-10 or the 17 ph 4?

interesting question, and I'll answer as best I can.

MAR-10 is a proprietary alloy that is very similar to 17PH-4 in most ways. Is normally thought as being interchangeable in it's normal state. But MAR-10 is still different in some ways. Nearly impossible to rust in deionized water, and trust me that's doing something. MAR-10 comes in the often desired pretreat form right from the steel mill in PA. Usually comes in at 30rc to 34rc, and heat treat is extremely consistent (similar to what I would expect from Timken if not even better). So it's harder than 17PH-4 right out of the box (maybe twice as hard). MAR-10 seems to have a little more nickel in it, and possibly slightly more chrome as well, and you'll know it when machining the stuff. 17PH-4 is tough and MAR-10 is like that stuff on steroids.

416 stainless steel is known as a high martensitic steel. That means your stuck with the retained martensite as you receive it. To the best of my knowledge
17ph-4 is not in that category (I'll have to look it up to be 100% sure). Mar-10 is considered a low martensitic steel. The down side with MAR-10 (always is a down side in everything) is the cost of the steel alone. A bar of that stuff will be over double generic 17ph-4 in cost, but it's also over twice as good. I have had holes gun drilled as deep as 16", and trust me it's a learning curve. Gun drills must have a custom grind, and ought to be Tin' coated. Coolants used are also special. Milling the stuff calls for a heady duty bearing pack as the tool pressure can be serious. Shavings alone come off glowing cherry red after passing thru the coolant, but that's what you want to keep the heat off the part you cutting. Seems to hold size very with virtually zero changes. The steel is extremely strong, and compared to 440c that's been hardened is like comparing CRS to 4140. I would estimate that a typical barrel blank 30" would have another hundred dollars in it, but also probably last twice as long.

I think Walther uses 17PH-4 or maybe 18-5, but think it's actually 17PH-4. Good steel for sure. 17PH-4 was developed for land gear struts on fighter jets landing on aircraft carriers in a high salt water area. MAR-10 in my uses (deionized water) held up better than 17PH-4, but (17ph-4) was still a light year better than 4** series stainless steel in any hardened form.
gary

 

[Trickymissfit]

just a short note concerning thoughts on drawing back a piece of steel's hardness at 1050 degrees. the draw back can start as low as 800 degrees with the complete temp soak! And of course the length of time. I'd completely forgot about that low of a temperature, and made a phone call to some folks in the know. I forgot to ask how we got by with a 900 degree soak in a plasma furnace, and should have. May have been saved by the .035" case I desired.
gary

 

[Cold Trigger Finger]

I checked Lothar Walther's site and it says their stainless steel barrels are made from LW50 steel.
I have no idea what that is? . Is it longer lasting than 416 stainless??

 

[idaho elk hunter]

I am not sure what "LW 50" alloy is. If I had to guess it is a nomenclature that Lothar Walther has named it for theirselves, (LW)? I can say that it is very hard to the point that many reputable gunsmiths have a hard time cutting a chamber. One has to slow the reamer down and flush a high volume synthetic cutting oil down the tube for it to cut right. It is also very hard to lapp compared to other barrels. If you go through the process you will have a great barrel that outlast all others even on the overbore cartridges. I just did one on my 26 Nosler and am breaking it in this week to send it off to get it nitride, It will be interesting to see how it does. Has others here had the same experience with these barrels?

 

[Trickymissfit]

I checked Lothar Walther's site and it says their stainless steel barrels are made from LW50 steel.
I have no idea what that is? . Is it longer lasting than 416 stainless??

i'm sure it's a custom alloy called out by Walther. On the otherhand I've read comments from Walther calling it out as a form of 17ph-4. He just rarely admits it. Most folks that know steels don't spec a 4** series for high heat. Just not a good combo, and chamber temps get serious. Usually starts with 330 or 349 and moves up the ladder. Problem with 330 and 349 is that they will not harden. In otherwords they are Austenitic. In that world you often can't have your cake and eat it. There are steels that would work very well in a rifle barrel, and withstand all the heat we could run at it. Yet they are extremely difficult to machine very accurately. Perhaps somebody will get brave and figure out a way to give us a barrel made of Hestalloy, and also figure out how to resolve it inherent harmonics. On the opposite side of the street, the Army did a little bit of experimenting with a hand full of titanium M14 actions that used a solid ceramic barrel. The groups sizes were bolt gun quality at the minimum, and that barrel could take anything you threw at it! Maybe it's time to be looking elsewhere.
gary

 

[Trickymissfit]

I am not sure what "LW 50" alloy is. If I had to guess it is a nomenclature that Lothar Walther has named it for theirselves, (LW)? I can say that it is very hard to the point that many reputable gunsmiths have a hard time cutting a chamber. One has to slow the reamer down and flush a high volume synthetic cutting oil down the tube for it to cut right. It is also very hard to lapp compared to other barrels. If you go through the process you will have a great barrel that outlast all others even on the overbore cartridges. I just did one on my 26 Nosler and am breaking it in this week to send it off to get it nitride, It will be interesting to see how it does. Has others here had the same experience with these barrels?

During my education process, and did a semester studying nothing but stainless steels and some form that are rather secretive to this day (military aps). Vito Mitkuss was the professor, and in his field he was a man you listened to. His first statement in the class stunned me! He simply made the statement that stainless steel is regular steel with lots and lot of nickel and chrome added to the compound. Of course it's also much more highly refined too. In that class he introduced us to the 5** series (never seen that one have?) And dealt with the new kids on the block like 15-5 thru 18-5. That class could well have been a two semester class as the data was constantly flowing in, and also changing almost weekly. He brought in men and women for lectures that were mind boggling, and made all of use feel like idiots with our questions. I'm certain now that there are some new alloys in the design desk that would solve all our issues, but most folks won't be able to use them due to the expensive learning cure in the machining processes alone. Big companies can do it fairly easily, but 90% of the barrel makers can't afford this.

Lastly when cutting 17ph-4, the coolant used can be an issue. Let alone the method for delivering the coolant. Your cutting threads? Often a good spray mist will get you by with the correct insert. Flood systems do well, but want pressure, and that can be a real mess. I have cut it with high speed with excellent results, and the tool pressure is vastly reduced if the cutting tip is ground right. But also a pain to learn. Reamers are ground just for this stuff, and a typical reamer won't get it. The finish reamer must cut a little more stock than we would normally think of due to surface work hardening alone. You just want to cut clean steel all the time. Won't tell you much about gun drilling (can't, but want to), but look for 2000psi of coolant. The coolant is special, and the grind on the drills are even more special. If you can get 3000psi, then go with it, as you need it. I used nothing but Pratt's to drill the stuff, and the Albions and Jap gun drills were not heavy enough. We put a lot of steel in the scrap tubs learning this ballgame, and I'll be first to admit it<g>.
gary

 

[Cold Trigger Finger]

Gary, thanks for all the knowledge you are sharing. Wow! Idaho, it sounds like you are building quite the rifle. It would be something to make a fast 6.5 have the throat life of a mid vel 6.5 . Now that I've got my Creed setup with a comfortable stockand a good scope that can do a lot more than I can at this point. I am shooting it a lot more. I'm wondering how long the barrel will last. Please keep us updated on your 26 Nosler project.

 

[Chandalar]

Are any barrel makers using Mar-10? Also would 4150 with a Melonite treatment give the highest strength and wear resistance?

 

[RH300UM]

I came across this thread and I was very interested. Learned a lot about. It ride and metals. I hate to see it end.
Any more experiences and info?

 

[Cold Trigger Finger]

Not yet from me. Need to get back up to the Slope for more gun money.

 

[RH300UM]

Not yet from me. Need to get back up to the Slope for more gun money.

Maybe I missed it but did you ever get your gun and/or barrel dipped?

 

[CRaTxn]

I have patiently waited for sufficient time to pass for some of these melonited / nitrided barrels to exceed their normal throat torching round count.

Would those shooting treated barrels please take a moment and update those of us contemplating using the process on;
the calibre,
round count,
Hawkeye bore scope viewed throat condition
and if those rounds were under rapid competition-prairie dog town or sane slower measured firing conditions ???
Thank you, in advance, for sharing your experiences and knowledge.
CRaTXn

 

[idaho elk hunter]

Are you waiting plenty of time and loosing patience for us to prove something for you? I guess the question is maybe being perceived wrongly for me. I definitely not buying a Hawkeye bore scope for others curiosity when the accuracy comparison of the 7mm RUM, 26 Nosler, 240 Weatherby round count goes up 1000 to 1400 rounds compared to other rifles I have built in the past. That tells me what I need to know. Hopefully this helps your curiosity.

 

[Pdvdh]

That sounds like impressive improvement. Thanks for sharing that info. You shoot WAY more than I.

I have one melonited barrel and will have a second in the next 6 months. But I'll likely never shoot out a single barrel in my lifetime - melonite treatment or not. There's probably a lot of shooters like me that never shoot enough to ever be able to provide a meaningful comparison in their lifetime.