Is the bore of this barrel melonited and it is considered a decent barrel? Thanks. HERE

looks to be inside and out

Yeah inside and out

Yes, and buy any melonited (Ferritic nitrocarburized) barrel you can get your hands on that will match you build requirements.

It basically involves submersing the steel in a molten sat bath. It is a surface hardening treatment that also blackens the surface. Comparable or better hardness / abrasion resistance then chrome with no affect on accuracy. There's some stuff on 6mmbr.com about it. If the bench rest guys are doing it then you know it doesn't mess up accuracy.

It's out of stock.

Yeah it is, and it is gtg. I got one for 69$ on labor day, it shipped incredibly fast, and is good quality.

By the sheer nature of how a barrel is melonited, it is nearly impossible to melonite the exterior only.  To soak something in a chemical bath at 1000 degrees for 45 minutes twice, would be very hard to do the exterior only unless you did it before the bore.  

 








 

Only down side I see is 1/9 twist.  If you shoot 55 & 62 grn 5.56 / .223, you should be good to go.

Do you plan to use a free float rail over the bbl?  Or go more standard and uee handguards with a front sight?

The bbl is set up to use a low profile screw set gas block Vs. the standard Front Sight Base with taper pins.

Don't know who actually makes this bbl, but it seems like a good value if it meets you specific needs.

As previously posted, if the barrel maker doesn't make a good accurate bbl to begin, then Melonited a bad barrel won't make it shoot better, bit will just resist rusting.

There would be no reason to nitride a barrel on the outside only.  It is the bore that is most important.   Nitride hardening will not make a barrel more accurate, but it preserves whatever inherent accuracy it has, unlike chrome lining, which is subject to plating irregularities which can degrade accuracy.

It's not just corrosion resistance.  Not only is QPQ SN treatment orders of magnitude better than chrome lining for corrosion protection, but the surface hardness will greatly improve barrel life compared to regular 4140 or even 4150 barrel steel.   It should surpass chrome lining for extended barrel life, but the data is still being accumulated to make long term projections.  Some members here are trying to survey to determine if there are 10k+ round nitride barrels.  We just don't know.  It is so hard that all machining must be done before the hot bath treatments, because once treated, the hardness literally destroys machine tool bits and reamers.

1:9 is good for up to 70 grain bullets and is actually better by some margin for 55 and 62 grain M993 and M855 bulk FMJ ammo.   I'm shooting 62 grain Barnes TTSX bullets (longer than most 75 grain lead core bullets) in handloads still under development that are already close to 1 MOA in a 1:9 nitride CMMG 16" carbine barrel.

But nitride is not a magic bullet.   Not knowing the actual barrel manufacturer would worry me a bit.

Sorry not meaning to mini rant but I want to chime in again.  About chrome lining and degrading accuracy.  While you won't be finding a chrome lined barrel at matches, or not usually, there is way to much made of chrome lining degrading accuracy.  It is always pointed out that chrome lining degrades accuracy like a chrome lined barrel will only achieve minute of man accuracy and is otherwise useless.  Maybe not every post but most seem to come off this way to me.  My FN CHF CL barrels are very very accurate.  Not sure they are in the same ball park as the JP stainless 6.5G I built, but they are in the MOA ball park (with some good hand loads)at least.  I would also say the same about my buddies Daniel Defense barrel.  These barrels are quite capable.  So while melonite does preserve bore accuracy like, say, a stainless barrel, the good CL barrels are, again, quite capable.  I am shocked at the accuracy my new FN 14.5" is delivering.  I recognize you will come closer to match accuracy with a melonite barrel but CL barrels are not necessarily limited to spray and pray.  My apologies if I misinterpreted anything, but I see this all the time and think it occasionally needs clarification.


 




 

Radical Firearms has the same barrel for $69.95 http://www.radicalfirearms.com/16-M4-1-9-Twist-Barrel-p/16m4-1-9.htm.

Certainly interested in seeing how melonite does years from now once they get more time, experience and information.  Its got a bright future...  Have to wonder how polygonal rifling will perform as well.

Topic Moved

Nitrided automotive crankshafts really eat up the grinding wheels on crankshaft grinding machines, requiring repeated wheel diamond dressing, especially the radius area.  Very rapid wheel wear.  It  quickly dull out reamers.  I can say this from personal experience.  Perhaps the penetration depth is higher in those applications, but the effect is significant.  This is no fun in a machine shop, but good for rifle barrels.

Concur. Also about chrome bores and corrosion, when is the last time anyone has seen rusty hard chrome? Harder, yup. slicker, in most cases, yup. Very corrosion resistant, yup. Possibly more velocity, maybe. More accurate a process, yup. Easier to clean, maybe.  But to make out like a chrome lined tube is prone to rust, ain't no way. It's kind of in there to extremely prevent just that (and longevities sake). I have a 11.5" fn chf barrel that stands it ground and some days out shoots my s/s poly barrels. I have no issue whatsoever with melonite, tennifer, qpq or how many other ways they come up with to do it but the whole salt bath beats chrome hands down thing is bullshit, IMO.

P.s. lug not directed towards you but your post out out points I wanted to expand on.

Agree with your points except for velocity. Meloniting a barrel will actually reduce velocity compared to the same barrel pre-melonite. The slicker surface reduces the pressure behind the bullet, which is what creates the velocity. Not a huge difference, but it's there. My testing with 3 different barrels yielded a 30-50 FPS drop depending on the ammo. My discussions with Superior Barrels (that does a lot of T&E compared to other companies) has shown that they've had similar results.

I would think the same concept would apply to chrome lined barrels, but its difficult to tell. Especially since it's not feasible to run the velocity tests on the same barrel pre and post lining.

I suppose this is why ARP barrels use a tapered bore.  I have no velocity problems with my ARP barrels.

 

Why are they grinding crankshafts after the melonite process rather than before?  And if it's being done to "turn" a crankshaft to put it back in spec, why is it out of spec?  If it's as hard and wear resistant as I see claimed then I do not understand at all.

With respect, you do not understand engine rebuilding and automotive machine shop operations.  These are engines that have been run for years and are being rebuilt, or are being built and prepped for racing applications.  The crankshafts either have wear and are being reground undersize for oversize bearings or offset ground to change stroke, or ground a different size to use different aftermarket connecting rods.  This is a very common practice.  Even nitrided crankshafts that may have many years and several hundred thousand miles can wear.  We are taking about very fine tolerances, specs that are only two or three thousandths of an inch wear, and machining to the next bearing oversize, typically .010" but precise and round to plus or minus two ten thousandths of an inch.  .0002." Sorry for the digression.

Well, with respect I've been a mechanic most all of my life, same as my father, same as his.

I fully understand.  Go back and read what I posted about turning crankshafts.  My point is if these magical nitrided parts were as hard as you say then I don't get how there are that many that need turning.  

And I'm not a nitride hater.  I just don't think the process makes wonder parts.

ETA:  While I don't personally know many people using nitrided parts in the automotive world, I come from a motocross background where nitride is prevalent.  It and DLC treatments can be found on parts ranging from tranny gears to fork tubes.  I know it works.  I'm just not decided on how much better it is.

As far as rifle barrels I know it is miles better than bare steel.  But until I see hard numbers/proof, I cannot say unequivocally it's better overall than a quality chromed barrel.

Yes a taper bore would work in the opposite way and increase velocity. Have we had this discussion before? I'm getting old.

Quite possibly, I was kinda putting that out there rhetorically.  But yea the ARP barrels have no problem with velocity, not the 3 I own.  Melonite is good stuff, or whatever SBN qpq you wanna use.   I just want to bring a level enlightenment to the conversation that non of these treatments are the magic pill they are purported to be.  Some will be better than others.  I love my ARP barrels.  I love my FN barrels also.  To each their own.  Your money your choice.  

You say this like there isn't already decades of experience with nitride/melonite as well as polygonal rifling in small arms barrels.

Just because it's not in US military use doesn't mean it hasn't been in use.

It also has decades of use in the automotive, nuclear power, oil & gas industries as well as other applications.

Please forgive.  I mean no offense.  Nitride treatment of industrial products and automotive crankshafts is a totally different thing than QPQ SN barrel treatment.  While the result is similar and the principles similar, the process is much different and involves chemically masking off parts which do not need to be hardened so that they can be machined with conventional tool bits, such as to balance the crankshaft counterweights while allowing the process to selectively harden the bearing journals.   Special grinding wheels are used when nitride surfaces are involved, as conventional wheels wear rapidly.  The process uses sealed ovens with nitrogen gas chambers and takes much longer, up to 100 hours.  This can produce a hardening that is up to .030" deep, much deeper than the typical rifle barrel, thereby permitting regrinding at least to the first oversize of .010" without having to re-nitride the crank.  Racing applications are usually re-nitride after the machine work anyway.  Part of the reason for nitriding racing applications is to make the surface far more rigid to resist flexing, not merely to increase resistance to wear, as those engines are controlled explosion bombs with short lives anyway.  Metal wear is far less an issue than fatigue.

As to wear, the hardening is about the same as with hot salt bath QPQ SN rifle barrels, the surface is about three times harder.  Even so, it does wear, and since the tolerances, especially in racing applications are so much smaller, as I mentioned, .0002" plus or minus, then even slight wear, or fatigue that closes the gap between surfaces rather than expanding it, can cause problems with high rpm, high horsepower engines.   Sorry for the diversion.

I agree, nitride barrels are not magic.  But they are significantly harder than 4140 or 4150 steel, provide protection to the entire barrel, not merely the bore, provide a level of corrosion protection if true QPQ SN that is orders of magnitude.better than chrome lining.   Whether they will produce longer barrel live than chrome lining is still an issue being debated and yet to be determined.  There are many variables involved in that debate and very difficult to control the variables in a manner that produces an apples to apples comparison.  Only time will tell.

MS556, we are in agreement sir.  I have a mechanical background, but certainly make no claims as a machinist.  I know the basics about what is done, but not much more.  Just like any field of study it can get DEEP.

Your last post makes perfect sense to me.  thanks!

One of the advantages of nitride over chrome is that the nitride layer in the steel is much thicker than chrome, it's integral with the steel, and tapers a bit into the steel so does not exhibit the craze cracking that chrome lining does.   Crazing starts the failure spiral as gas erosion is exposed to the underlying barrel steel.

And regardless of this the FN barrels button and hammer forged have still been known to get 1000's of quality rounds down range.  Under harsh conditions.  While this may pan out for nitrided barrels there, at this time, is no long documented history of it. I have no particular issue with meloniting with the exception that most people get on here and deliver a message of the "magic pill". When it all plays out we will see if there is a clear winner.  Right now there is no history of data that makes melonite a clear longevity winner.  There are however lots of projections that say under some conditions it could win out.