Melonite barrel treatment

[Pdvdh]

Hey Guys here's a quick recap of what I've learned after nitriding nearly 100 chambered barrels and actions over the last 3 years.
1) Some nitriding companies run the solution at the stress re-leaving temp, for our barrels that is 1050F and all you will end up with is a really expensive black barrel. If you are having this done by yourself get the S/R temp and save your self that headache.

Hope this helps!
Chris
Benchmark Barrels

Chris,
A little fuzzy on the above point. Are you saying the stress relieving temperature of 1050F is the preferred temperature for nitriding? Or that 1050 is a poor temperature for nitriding? What nitride bath temperature are you recommending?

 

[elkaholic]

Chris,
A little fuzzy on the above point. Are you saying the stress relieving temperature of 1050F is the preferred temperature for nitriding? Or that 1050 is a poor temperature for nitriding? What nitride bath temperature are you recommending?

My understanding is, 1050 and you are toast! When I talked to the nitride tech, he gave me the exact temp they were shooting for and it is JUST under where you lose temper, but I can't remember what that is? I think it is in the high 900's?.......Rich

 

[Trickymissfit]

Gary...that's a little scary man that it has something to do with stress reliefthinking your bore dimension could change by nearly a thou. It must not apply to Stainless or chrome moly or they couldn't do this. I was told by the experts that it will not change the dimension in the barrel hardening process at all. I will say this, however; I remember the muzzle brake requiring more torque to align as it previously did on the barrel? That could be just a residue problem though?.......Rich

chrome moly yes, but never tried to nitride stainless steel. The issue is nothing new as I've seen D2, and S5 & S7 do the samething. Nobody seems to have a finger on the subject, but has been discussed a lot. Now .0009" one way or the other is the extreme, and most of the time will stay in the working window. On the otherhand I've had parts change size after being cryo'd, but never worried much as it was being cut again. I'm a betting man that it has something to do with stress relief.

The issue with the muzzle brake might have been a slight damaged thread when you took it off. Very fine threads are prone to this, and often destroyed when used with Loctite. I always polished the male thread form's OD a little bit as the sharp vee often interferes with the root. Stainless threads may start out good, but often get messed up on removal. Some of this is due to the metal itself and some come from the fact that stainless steel doesn't lube well. Sometimes you get a problem with dissimilar metals being used, but can't ever remember that with stainless and carbon steel. Aluminum is another ball game! Back to the threads being tight. Buy a can of Clover lapping compound (7A). The finer grades are like water, and will remover any hiccups easily. Another issue is that if you cut the barrel threads on one lathe, and do the muzzle brake on another you will be fighting two different lead errors. Now we're often talking less than a thousandth in a foot, but it's there.
gary

 

[deadlift]

We have our nitride spec'ed out at 970F and that produces a good hard finish. BUT this will vary per each barrel manufacturers stress re-leaving temp. 70 degees low of final S/R temp is where you want to be according to H&M.
Chris
Benchmark Barrels

 

[Pdvdh]

Thanks for clarifying.

 

[bigngreen]

We have our nitride spec'ed out at 970F and that produces a good hard finish. BUT this will vary per each barrel manufacturers stress re-leaving temp. 70 degees low of final S/R temp is where you want to be according to H&M.
Chris
Benchmark Barrels

That is excellent info, especially since I've been rocking a number of Benchmarks lately and really want to go with some nitriding soon.

 

[Trickymissfit]

My understanding is, 1050 and you are toast! When I talked to the nitride tech, he gave me the exact temp they were shooting for and it is JUST under where you lose temper, but I can't remember what that is? I think it is in the high 900's?.......Rich

your on the right track, and to go deep I need a good heat treat manual or else hunt up some steel manufacture's data books as they often come with that data. I add a lot of steel normalized thru my years. and 1050f seems a tad light even for good quality hot rolled plate maybe 1200f to start with. I do remember one normalizing furnace that ran close to 1400f, but it was special (owned by TACOM). Was a high speed unit for quick work. A typical prehardened blank at 1050F will start to draw back quickly as the soak gets deeper and time lengthens in duration. I wouldn't, but it's not my piece of steel as well. I would use nothing but plasma or gas injection in the longest process allowed. The 900F is what they had these furnaces setup at, and never questioned the thoughts of the metallurgical engineer that setup those processes.
gary

 

[Cold Trigger Finger]

So can Ruger stainless steel actions and bolts be treated or is there a problem because they are cast??

 

[Trickymissfit]

So can Ruger stainless steel actions and bolts be treated or is there a problem because they are cast??

Ruger stainless steels that I've been around seem to have a higher Rockwell than say a Remington or Savage. But I've drilled and tapped holes in them using carbide taps. The newer Tin' coated cobalt stuff might work as well. Never tried using it. The 416 alloy is a crap steel on a good day. Carries a lot of retained Martensite, and that's a bad thing. Most will never know, but when you are looking a minus twenty degrees it shows it ugly head. Many will disagree with my comment, but many are also clueless in metallurgy. Steel manufacturers will tell you differently. Weatherby even issues a warning (they use 416). There's a really simple way out of this, but will add about a hundred dollars to the rifle. One could probably do a Ruger without any problems, but if it were me, I'd just do the barrel and maybe the bolt. Castings are a different ball game, but Ruger is also one of the better folks at doing investment castings
gary

 

[Cold Trigger Finger]

What happens at-20°F . ?????
That is just a nice winter day here. I regularly shoot down to-45°F and if a shot presented itself at-50 I would take it.
I have noticed higher pressure down that cold tho . My theory is that the bore and chamber constricts in the cold.

 

[shortgrass]

I would not have a factory barrel or action treated. It'd still be a "factory" action, much like any other 'up-grades' that are offered. By the time you paid to have the action 'trued' and then Melonite treated you could easily buy a Stiller (or a BAT). And factory barrels? I'd not waste the $$$. I've got a BAT that I bought several years ago. It's not Melonite treated and is mighty 'slick' as it is. I'm a firm advocate of Melonite treating custom barrels, I've had positive results as have my customers (probably had about 40-50 done). Especially chamberings that are known as "barrel burners". Treating custom actions, not so much. I've never worn an action out (I've been shootin' [seriously] for 40+ yrs.)! One of my high school graduation presents (class of '74) was a Remington Varmint Master chambered in .22-250. It's been re-barreled about three times and the action's not worn out, by any stretch of the imagination. A 'custom' action will hands down be 'slicker' than about any factory offering, anyway.

 

[Trickymissfit]

What happens at-20°F . ?????
That is just a nice winter day here. I regularly shoot down to-45°F and if a shot presented itself at-50 I would take it.
I have noticed higher pressure down that cold tho . My theory is that the bore and chamber constricts in the cold.

high martensitic steels don't react well to extreme cold temps. Not just Weatherby's disclaimer, but also Sako's as well. Not in the product design, but all metallurgical. When doing a metal quench, one of the main goals is to get rid of as much retained martensite as possible. With 100% as a goal. If you get rid of 75% you did a good job, and expect to get rid of 40% with a normal quench in heated oil of an unspecified type. So what's all the hype about martensite and steel? Strength! The more retained martensite the lesser the strength, and then you factor in the extreme cold to make the above even worse. There are trade secrets to help fight the martensite issues, and I told you one, but just enough to get you in trouble. A barrel cut from 17PH-4 will be a zillion times better for what your doing at a minus 50 degrees, but a barrel cut from MAR-10 will be that much better than 17PH-4. Most barrel makers won't know how to do it.
gary

 

[idaho elk hunter]

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

 

[Cold Trigger Finger]

I don't use push feed actions for working rifles. Too many little parts that can freeze up, too many things go wrong with them. The cold increases pressure and rotating extractors are prone to breaking or cutting part of the rim off. Plunger ejectors easily freeze in place. So while Bat's, Stiller's Defiance ect may be the Porches, Lamborghini's and Mazzaraties of the rifle world. I need more of an off highway Kenworth or a Rollagone.
No doubt they are totally awesome in a more temperate climate but for my needs , nope!



Enclosed bolt faces create plenty of problems also.

So for me, spending a bit on treating the bolt and action to make it even slicker is money well spent.