Barrel hardness

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by meatyrem, Mar 1, 2011.

  1. meatyrem

    meatyrem Well-Known Member

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    I have heard of different barrels being " softer " or " harder " than others. Of theses barrels- brux, broughton, krieger, lilja, pac-nor, hart, rock, and many others I did not list, is there levels of different hardness? Which would be hardest to softest? Is this a rediculous question? Does it make much difference if there is diff levels of hardness. What are any advantages? Thanks for any help
     
  2. EddieHarren

    EddieHarren Well-Known Member

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    Most SS barrels, being made nowdays, utilize 416 stainless. One of the reasons is the alloy's machining properties. 416 can be hardened but I know of no barrel makers that do this.
     

  3. Kevin Thomas

    Kevin Thomas Well-Known Member

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    Yes, there are differences here, depending on whether what heat treating processes the barrels have been put through. Some treat them to soften them before buttoning, some don't. The speed with which they're buttoned and the finished diameter they're reamed to all go into how hard the maker will want the barrel to be.

    Similar situation with cut rifled barrels, and the machining qualities are what the maker's after here. Not sure what you're after here, since this doesn't necessarily mean that a barrel will last longer, or burn out quicker. A consideration, yes, but not the only factor, and I doubt too many barrel makers will reveal the specifics of their entire process. Most guard that info pretty closely.
     
  4. sp6x6

    sp6x6 Well-Known Member

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    I also read on LRH, that some bench shooters and others are nitrade,spell, treating, which I guess hardens. Sounded very interesting
     
  5. Kevin Thomas

    Kevin Thomas Well-Known Member

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    I saw an example of that last week, but that particualr nitriding process could only be applied to CM barrels, not SS. Kicked the Rockwell hardness up to somewhere around 70 and looked very good. Most of my barrels are SS, but the next time I go with a CM, I'll definately consider this one. Very impressive stuff!
     
  6. Trickymissfit

    Trickymissfit Well-Known Member

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    Boy that barrel must have been in heat for a long time! I wonder how deep the case went. I never tried to nitride any 400 series stainless, so don't even know what the process would be for starters (keep in mind that I'm or never will be a 400 series fan).

    Carbon steel barrels are usually cut from something like 4350 (I suspect everybody has their own private alloy number). Most stainless steel barrels are cut out of 416 because they know how to work with it, and not because it's the best there is. Actually 410 or 420 would be better from the data I have. But once again much harder to machine. Some folks are now using 17PH4 rearc melt stainless. This stuff is not for the faint of heart to machine, but once you learn the process it's fair. Wether they buy it in certified preheat treat lots I don't know, but suspect they are. It'll take more heat that 416, and has better strength & wear properties. A similar steel is MAR-10 from Baldwin Steel in PA. Considered interchangable with 17PH4, but has better maching properties. It only comes in a pretreat form, and special lots of steel with different Rockwells can be had. This steel will not rust. But on the downside is about twice the price per pound.
    gary
     
  7. MontanaRifleman

    MontanaRifleman Well-Known Member

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    I'm not sue which process Kevin is referring to, but the process that Joel Kendricks does is OK on SS. It can not be done on some actions though, SS or CM. Rockwell hardness of about 65-70 on the surface.
     
  8. Kevin Thomas

    Kevin Thomas Well-Known Member

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    I'd have to find out what alloy he's using for his CM barrels, but the finished sample was very good looking. Damn sure better have any and all machining done one these beforehand, or you'll go through some tooling trying to work this stuff. Finished out at a very dark tungsten grey with a satin type finish. I was already to have my 338-06 done, but it's a SS barrel. Maybe the next one.
     
  9. Trickymissfit

    Trickymissfit Well-Known Member

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    what I'd love to have known is what the barrel slugged at before nitriding, verses after nitriding. Reason I ask is that I've had steels shrink as much as .0009", and others grow a similar amount! If the barrel shrinks .0005", it also means the bore opened up a similar amount. But if it grows, then the bore shrinks. But for a disclaimer, I was using gas for 29 hours to obtain a .035" case at 64RC
    gary
     
  10. Trickymissfit

    Trickymissfit Well-Known Member

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    I've had to drill and tap holes in steel that's been nitrided in the past, and it's not for the fain of heart! But you can use a sinker EDM in a pinch.
    gary
     
  11. Time Killer

    Time Killer Well-Known Member

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    FYI, nuetral hardening on 416 SS only yields a maximum hardness of around 45 HRC.

    Maximimum attainable case from nitriding is .008" in 48 hours...but is not recommended for a severe corrosion enviroment.

    I happen to have my SS barrel off. I will go check the hardness and post later as I am curious as to what it is.
     
  12. Kevin Thomas

    Kevin Thomas Well-Known Member

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    MontanaR,

    Couldn't tell you what the process was, as I didn't ask. I was visiting a friend whose a barrelmaker, and he sent this one out as a trial to see if he wanted to use these folks as a regular supplier. Hadn't decided yet, but he was very impressed with the results. It looked pretty sexy, too.
     
  13. Kevin Thomas

    Kevin Thomas Well-Known Member

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    Gary,

    Dimensional changes I can speak of; zero. First thing he measured and a primary concern for him. we talked for quite some time about chrome linings, hard chrome plating, various other surface treatments. The fact that this one showed zero dimensional changes was a real biggie for him.

    Know what you mean about these changes, too. I've had quite a few pistols and revolvers HC plated over the years, and they virtually all come back needing to be refitted and lapped in on themselves (in the case of pistols). Hard as that stuff was, redrilling holes would be a real pain.
     
  14. hammertyme

    hammertyme Well-Known Member

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    Barrel hardness does make a difference in barrel life in my experience. AT one time there was a gentleman that bought Green Mountain 2nds blanks. He cut them to length, crowned and chambered them and sold them for a very good price. I got some of his blanks and welded hinge blocks on them for Encores. When I checked the hardness of the weld to make sure it wasn't brittle I also punched the steel. C scale hardness of the barrel was 7R. The barrel and the maker did not last very long.
    If you speak with a number of barrel makers I think you will find that the good ones are trying to come in at around 28R.

    SInce I have been NITRIDING my barrels and actions for about a year and testing them and the people that do the process any number of ways I think I can accurately speak here.
    1. I have yet to find anything but positive except # 2
    2. Not everyone Nitriding does it the same and some do a very poor job.
    3. I and a barrel maker took measurements before and after Nitriding a barrel. Did you know that Savage does not heat treat their awesome shooting barrels?
    4. Benchmark barrels laps their barrels several times including after Nitriding they do a clean up and pin lap to make sure the barrel is exact when they send it or install it on your action.
    5. If your actions are steel you can Nitride the action as long as the person doing it knows to keep temps under 1500 degrees and in that temp for an hour or less. We have punched several Savage actions. The average loss of harness across the board is 1-2 rockwell. Some 42's actions were found at 41 or 40 R on the C scale. The rear bridge was typicall 38-40 if I recall correctly. It/they also dropped an average of 1-2 points.
    Understand also that different people think different things but the general idea is the depth of the Ferratic hardness is 2-3 thou. Some will say more makes it brittle. Not sure where that one came from since a typical action is a whole lot of uneffected strong steel under that .002 or .003 surface hardness. The Ferratic Nitride process that has been used on mine and friends stuff is under 1200 degrees and for less than an hour. Basically what your smith does for stress relieving except Niride is in a salt bath and not an oven.
    6. I have 9 Nitrided barrels. Some I broke in first. Some I Nitrided first. I have 9 bugholing barrels and I am getting ready to send two more barrels to Benchmark. One stainless and one Chrome Moly to be Nitrided. I am so sold on this process for my Alaska hunting needs. 500 hours of salt spray testing without any sign of corrosion is good enough for me. It looks like a $400. ble job and to date it has destroyed all competition the military has stacked it up against for wear longitivity.

    Note: Nitride is first put in a 950-1200 degree bath for roughly and hour. Then it is dipped in an oil bath at 750. The first time the barrel looks like a gray color or white/gray. The second dip at 750 gives it that blue black or carbon black finish. Different dippers have their own ideas how to do this process. Basically it is the same concept.

    Hardness comparison: I have an e-mail from someone which was sent to a smith on here. The man referred to wanting a brake because he bought three el-cheapo's from someone. Two of the brakes galled so bad they had to be cut off the barrels and re-crowned. He wanted a different brake before the same thing happened to barrel number three. I know the person selling the brakes quite well. I turned him onto a long time machinist friend and I know that the material used for some of those brakes were made out of a steel/lead material. Those in the brake business Like Daryl Holland Jim See and others have their brakes heat treated.

    Hardness matters from my perspective.

    Some of us built 6.5 WSM's after learning about Nitride. I have a friend of a friend that now has 900 rounds through his barrel and it looks just like the day it was installed. THey are borescoping there hotrods quite often and documenting just how much difference NITRIDE makes on barrel life.
    7. My 19" handgun barrels range from 95-135fps more velocity than without Nitride and there are NO exceptions. Same load as before Nitriding.
    8. I have quite a number of skinny little hunting barrels. I have shot only three shot groups through many of these barrels for 40 years. AT 5 shots with the big powder capacity cases of today the barrel is mighty hot. SHooting 5 shots through a Nitride barrel and the barrel is warm. AT 7 rounds we are really warm.

    Lastly: My pride and excitement currently is a Savage takee off never fired 300 RUM barrel. Cut to 19" and was Nitrided and I received the barrel and brake in dirty right from the tank condition. It currently shoots into one hole with two bullets and with that same load of H1000 the 165gr Accubond and the 168gr Barnes TSX have shot .2 and better six times at 100 yards. Velocity- well past 3200fps. 95 grains of H1000- Not responsible for your loading practices. Start low and work up. I have added two grains more powder a couple of times after Nitriding and we can sure smokem!

    I am so happy someone took the step from the tooling industry and turned me onto NITRIDING!

    Neal
     
    Last edited: Mar 1, 2011