Hey Guys,

I'm getting back into ARs and I have a barrel question for you.  Stainless steel or Melonited, which is better and why in your opinion?
I've already got an AR with a 20 inch Wilson Combat barrel chambered in .223 Wylde which shoots great.  Thank you for your thoughts.

Okie

More information on the intended purpose of the rifle?   Workhorse? Plinker?  Bench rest?  Etc.  between the two for general purposes I would go melonite.  But if you want ultra accuracy you may find stainless to be your need.  I am sure there are some plenty accurate melonite barrels available.  

This rifle would be an all around plinker/range gun, since the AR with the Wilson Combat barrel is my bench rest rifle.  I did some more research and found a thread on ARFcom that answered my main question.
I like the durability of melonite, but I have to face facts that I won't be putting thousands of rounds through this rifle like my AK74.  Accuracy matters more to me when we're talking ARs.

Look for a SS Noveske barrel or Rainier

I don't think there is any downside to melonite treating of an AR barrel....

From what I have seen, its les expensive than CL on a steel barrel and adds durability to stainless....

I helped my dad put together an AR with a stainless barrel. The melonite was $35 I think while CL was $50...

You already know the quality of the Wilson why not buy another for this rifle in whatever configuration you are looking for?

Even for a less precision build, I recommend QPQ SN (melonite) treatment of the barrel.   It surface hardens not only the bore, but the entire barrel.  It is far more corrosion resistant than chrome lining, and it preserves the rifling in pristine condition, unlike a plating process.   The barrels will last longer than stainless and at least as long, based on early data, as chrome lined.  The exterior hardening makes them extremely resistant to cosmetic damage, too.  You just about have to use a diamond file to cut into that surface.

I am getting 1 MOA accuracy from an inexpensive 16" carbine barrel from CMMG that has QPQ SN treatment, provided I use match ammo or my own careful handloads.  This is a sample size of only one, but it is fairly common for good carbine barrels so treated to have this level of accuracy with good ammo.

WOW, no you can drill it with a steel bit, does not require a diamond file, but it is hard.  Not sure what early data you are looking at, but it would depend on your firing schedule as to how long it would last.  And I am not sure any early reports of hard use show it lasts any longer than Chrome lining.  I believe it will out last a stainless barrel potentially.  It is a good way to process a barrel but it is not a magic pill.  Just depends on what you want to do with it.  

 

I was looking at LWRC's reports on testing their piston carbine with QPQ SN barrel with the known to be hard on chrome M855A1 copper ammo.  I don't have better data, nor does anyone else, but as between stainless and QPQ SN, the latter wins hands down on all counts.   Heck, national competition shooters are now having their stainless match barrels QPQ SN treated to try to extend the short gilt edged accuracy of their sub MOA barrels.  Only time will tell if the process produces higher barrel counts than chrome lined.  We simply do not know, and no one seems interested in performing controlled studies.  We know its corrosion protection is far superior to CL.  What we don't yet know is wear resistance compared to CL.

I stand by my statement, and it is well-recognized in the industry, that nitride surfaces cannot be machined with conventional cutting tools after treatment and are extremely difficult to grind. They are present challenges to welding.  This is very hard stuff.

I really wish we had more hard data as far as extended life. I saw several forums where match shooters were sending barrels off but i just wish we had a couple side by side tests to show what was gained.

Not being smug and not trying to engage in a pissing match.  We have drilled them for pinning and dimpling gas blocks.  No doubt they would be harder on bits, but they drill out just fine with regular tooling.  Nothing special required to get the job done.  Maybe if you do a hundred a day but the few we have done required nothing extra hard.  

 

I don't disagree with your experience.  Our shop cannot bore large holes, do reaming operations, or surface milling on nitride without quickly dulling out standard tooling.   Special bits and wheels are employed.  No, the trestment is not magic, but there is a reason all shops I know have the nitriding done after all machine operations are completed, and it is not just to reharden a previously treated surface, as important as that often is, too.

OP, I'd go with melonite over stainless every time. Same accuracy, longer life, lighter (generally). It's win-win. Of course, all of this presumes that you're comparing a HQ melonite barrel to a HQ stainless barrel - first and foremost you want a quality barrel, regardless of type. As for people who get their stainless barrels melonited.....I don't see the logic.

One of the advantages of stainless steel is the rifling can be cut more precise than cmv steel.  That's why we see match barrels made of stainless.  It's downside is it's softer, and barrel erosion is accelerated.  A melonite treatment to a stainless barrel would be the best of both worlds.  A precision cut barrel with reduced wear.

There you go. I learn something new every day.

The above is not necessarily true.  I understand that the melonite process works great on carbon steels.  It does make stainless harder, but the process seems to give up some of stainless steel's inherent corrosion resistance.  The best option is to use a carbon steel barrel for melonite treatment.

Melonite's calling card, one of its biggest selling points, is its corrosion resistance, so I don't buy that. Melonite is virtually impervious to corrosion, whereas anyone who has owned many stainless components can attest that stainless steel is, at best, corrosion resistant.

You and I both.  Lug1 and I were just discussing this.

Yes.  The corrosion resistance of QPQ SN, that is the correct name for the process also called Melonite, is best on 4140 and 4150 steel.  It is somewhat less effective on stainless for technical reasons, but stainless so treated is still much harder and much more corrosion resistant than plain stainless.

Edit to fix crappy autospell, which I have now turned off!

Melonite is more and less effective depending the elemental content of the steel.  This is one of the reasons it doesn't particularly increase the corrosion resistance in some types of stainless.  

 

Lug, I wonder if one of the types of stainless barrel steel would be more "accepting" of the nitriding process than another?  As I understand it, 416/416r merely has a higher sulfur content than 410 ?

I was just curious after reading your post.

Just a guess on my part, but I'm betting it's the chromium content displacing the iron content.  But I don't say this with certainty.  

I have a long term project in which I'm recording bbl throat wear Vs jacketed rounds fired, primarily in 300 Blackout, but have started same in 5.56/.223.  I normally fired 5 shots and let the bbl cool before more firing.  I use a variety of bbls.  Although I have a long way to go, and hope I live long enough to see this through, here are some results so far in 300 Blackout:

Plain 4140 steel wears the fastest (not to imply it wears fast in and of itself, just faster than the other types of bbls)
Stainless wears the next fastest
4140 nitrided next
4150 nitrided next
chrome lined 4150 least (note:  I only have that one chrome lined 300BLK bbl, but have one from another maker on order with 4140 steel and chrome lined and hope to have it around Thanksgiving...not many places offer chrome lined in 300BLK)

This is after around 1200rds through each (some less; some more).  Historically, to the US military, when the throat has advanced 1", the bbl is considered worn out for accuracy  That has coincided with my wearing out a few plain steel 30/06 bbls.  I don't have enough data to see a trend in 5.56/.223 bbls yet.  All data obtained is done in the normal course of my plinking/shooting targets/hunting.  I'm retired and try and go shooting twice per week.  I cannot say any one type is more accurate than another, only that accuracy in the 300BLK seems to vary by the individual bbl.  My 16" Daniel Defense is the most accurate, buy my 10.3" Daniel Defense is of average accuracy.

Thanks for the info. Could you hazard a guess on the expected life difference between the untreated barrel and the treated ones?? ie 4140 5k, stainless 5500, melonited 6k etc.

I understand that every barrel is different but some kind of that's to go by would be nice.

WholeBunches:  Thanks for the post!  I am interested to see you post a long-winded thread

I will try, BUT:

What I'm seeing is more rapid throat wear in the first 10-100 rounds, followed by a LONG (I have no idea how long) period of slow wear.  So, ignoring that observation and a-s-s-u-m-i-n-g wear is strictly linear in speed, in 300BLK, shooting jacketed bullets (about 95% supersonic and 5% subsonic) using H110 95% and AA1680 5%, and the formula 1" divided by throat wear in inches and multiplied by jacketed rounds fired:

Stainless from Core15, 416SS I believe, will go 12,540 rounds before the throat has worn 1".
Chrome lined 4150 from PSA will go 17,227 rounds.
Nitrided 4150 from Daniel Defense will go 15,200 rounds (both of my DD bbls are wearing about the same rate).
Nitrided 4140 from AAC will go 13,606 rounds.
Plain 4140 from Remington (Model 700 rifle) will go 11,820 rounds.

I also have plain 4140 from AAC (Handi Rifle) and Delta Co Arms (now out of business), but it's hard to include them, as I fire a lot of GI frangible bullets (made of compressed bakelite and powdered lead, I'd say slightly harder than hard cast lead) through them...those bullets wear less than jacketed.  I'd guess that shooting such bullets would result in 2.5 times as much bbl life as with jacketed.   But looking at the jacketed rounds fired through them, I'd estimate they wear about like the Remington Model 700.  Also, in the 300BLK, plated bullets seem to wear just as much as jacketed ones do. Because of the small amount of powder being burned in the Blackout, I feel the bullet makeup has more to do with bbl wear than with other rifles using more powder.   I've fired a total of 13,922 300BLK rounds in all of my 300BLK rifles and uppers.  Firing .310-.311" 123gr 7.62x39 bullets doesn't wear the throat any more than shooting .308" jacketed bullets.  I use Nosler 125gr Ballistic Tip bullets for hunting, and about 1:30am last Sunday took my 5th hog with a Blackout.  I am a Blackout Nut.  Glad I stocked up on components before the long shortage began.  

I have a Ruger American Ranch in 300BLK on order, but Ruger won't tell me what the bbl is made of.  Robinson Arms will be sending a 4140 chrome lined 300BLK bbl for the XCR-L.  Per the owner of Robinson Arms, their testing showed that chrome lined 4140 lasted a few thousand rounds longer than nitrided 4140 in rapid firing so chrome lined 4140 is what they use in their barrels instead of nitride treated.

Cool man. Thank you. Hopefully with the nitrided barrels becoming more prevalent we will start seeing more data that will give us a better picture.

Interesting!

Bushy does the SS barrel WITH Melonite LINK

Interesting.  I would love to hear a range report from somebody.  Guessing its probably a good shooter.  Looks alright.  I am very interested to see what melonite does long term to stainless barrels.  On one hand it could improve their long term usability with longer superb accuracy.  On the other hand it could make the stainless brittle and when micro fractures start forming in the chamber and throat it could cause near immediate barrel death by chipping and such.  Stainless may only maintain sub MOA for a just a few thousand rounds if that, they tend to fade away.  I do not not know if melonite changes it that.  I suppose you could make a case that it could.  But I have high hopes for melonite stainless.