In the last few years I've been seeing more and more of these.  For you guys that actually own one, what's your thoughts (ie corrosion resistance, accuracy, ease of cleaning)?  Do they do what they are advertised to do?  My only experience with it is the slides on my Glocks, and Xds.  Not asking which process/coating is better, just looking for real world experiences with them.  TIA

Just got my Krieger barrel back from it, will be able to report this weekend. Unfortunately my velocity data won't be valid because the velocities I too prior to treatment were in the summer, and it's winter now.

Only have a few thousand rounds combined on 3 melonite barrels I have owned, down to 2.  Yea they wipe down a little easier.  After looking at what real world evidence(precious little) to go with, it remains unclear if it is a real competitor for long lasting chrome lining.  My melonite barrels are ARP brand.  They are accurate.  As far as Glock and XD go, yes respectively they are Tennifer and Melonite, and their slides wear very durable.  Their barrels are also treated.  But keep in mind both brands barrels are also hammer forged.  I think that figures into their barrel durability also.  There is a VERY REAL benefit to SBN, but is it as advertised 3-4 years ago as the longest life barrel treatment available?  That remains to be seen.  I feel like it will greatly exceed any unlined, untreated barrels.  I am not sure that it will out last any FN CHF extra thick chrome lining barrels.  All of this will vary with your shooting style, of course.  I give SBN a thumbs up.  I do not give it the barrel savior title that was advertised when it started to become popular.  I do want to know more about the SBN hammer forged barrels that are emerging like the Daniel Defense S2W line and then the LWRC barrels.  The jury is still out on some of the properties, but some properties are verifiable.  I think it could potentially make stainless stay pinpoint accurate longer, I personally have no evidence of that.
 

This is a very accurate, faithful representation of the facts as we know them.  I'm one who holds the hypothesis that QPQ SN treatment of an otherwise equal barrel that is chrome lined will have similar barrel life, but the data has not emerged to prove or disprove this.  The data is clear that QPQ SN has superior corrosion protection, and to the entire treated part, not just a barrel bore.  The data is clear that because the process works at the molecular level and not a plating, it does not disturb or alter rifling. That may help a barrel achieve its optimal accuracy potential.  Bench rest shooters at the national level with high grade target barrels are having them QPQ SN treated to extend barrel life, which is very short otherwise for gilt-edged accuracy.

Not all QPQ SN treatment is done at the same quality level.  Very experienced companies should be used. If buying a barrel, try to find our which company is doing the nitride, because it is rarely the same company making the barrel.  Different processes and different substrates (the barrel steel) produce different results, including how deep the molecular hardening penetrates into the steel.

There are issues that can arise in treating a barrel after it has been assembled to the barrel extension.  There are reports that the thermal expansion and cool down can loosen the extension and essentially ruin the barrel because it is virtually impossible to line up the gas port properly afterward.

Good manufacturers nitride the parts separately first.  I would not feel comfortable sending a finished barrel off for treatment, but would not hesitate to have it done prior to final fitting and torquing of the extension.

I have only one nitride barrel and I am only at about 2,500 rounds or so. I cannot address barrel life. It is very accurate for an otherwise "ordinary"  gov't profile 16"  carbine barrel.  It is virtually impossible to scratch or marr it and rust is simply not on the radar. I suppose if I immersed it in saltwater for weeks it might.  I understand the cbemistry involved.  I like my sample of one. Done right there are real benefits. Nitride barrels, however, are not a perfect solution. There never is.

Thanks for the replies, I think I'm going to get one of CMMG's 16" carbine barrels, and try one out.  All of my other ARs are sporting CL or Stainless, so I'll have something to compare it to anyway.

I don't have many rounds through my 2 (used to be 3) nitride barrels to comment on durability as to barrel life. But I can tell you that both of them cost WAY less than an FN CL/CHF barrel (which I have on another rifle) yet is equally as accurate. I also prefer the glossier look of the nitride as well as it's durability (as said, good luck scratching it. Park scratches WAY too easy for my tastes). Since the treatment is so durable, rusting just isn't a concern (unlike park). I'll not buy anything but nitride from here on out.

My experience with Melonite has been mixed.  A few things you have to watch out for with Melonite is that the process will likely loosen the barrel extension, so make sure the maker checks for that. Due to this, the gas port hole will be drilled afterwards.   The melonite process also leaves a hard rust like residue in the bore that is not easy to remove.  Be prepared to use up a bore brush or two and lots of work before shooting it.   My ARP barrel took a days worth of work cleaning before a patch would go through smooth and come out clean before I could shoot it.  The rough spot left from when the gas port hole was drilled took hundreds of rounds to smooth out.   Melonite for sure hardens the steel,  when trying to drill the gas block dimples and hole for the cross pin, a new Chicago Latrobe cobalt bit could barely break through the melonite.  It pretty much wrecked the bit.  I can easily drill a CHF DD barrel with one of these bits.   Another thing I feel should be mandatory on melonite barrels is  they should be hand lapped before the melonite process This is  because any rough marks in the bore are not going to smooth out due to how hard it will be.   My ARP barrel now has over 1200 rounds and the TE is still the same as when it was new, but it still copper fouls badly.  It is more accurate with a variety of ammo vs a chrome lined bore.  It will consistently shoot XM855 at 1.5" groups vs 4.5" groups from my Noveske N4 chrome lined bore with the same ammo and scope.    My Chrome lined bores will clean up much easier with just a brush and CLP.  The melonite bores require copper solvent and a lot more work to clean.    So far I think my melonite barrels will hold up as well as a chrome lined, maybe even better.  They are more accurate than chrome lined but do have a few drawbacks.

Wow, I have had 3 ARP barrels, still have 2, a good friend of mine has had a minimum of 3 ARPS, a couple voodoo's and an Aeroprecision.  We have not experienced your experiences.  Every ARP barrel we have had has cleaned up new with a patch or two or one run of a bore snake.  Copper fouling?  Shoot it to foul leave it till your group sizes change.  Normal cleaning for me is super easy, a shot of Hoppe's or Birchwood Casey solvent and a run of the bore snake, and they are super shiney clean.  No particular issues with any of them copper fouling or groups opening up.  The whole rust thing in the bore I have NEVER encountered.  The first patch has come out black on it but thats about it.  I have never had a problem with barrel extensions coming loose.  I have read about it on people that nitrided their  barrels post production having barrel extension troubles.  All our ARP barrels came pre dimpled.  I like my ARP barrels for accuracy.  I would still favor and FN CHF barrel for most of my AR's.

 

I haven't had that issue either with my Voodoo barrel

I didn't mean for it to come across that the ARP barrels were bad, but they do take a lot of cleanup out of the box from the melonite.   It still copper fouls bad, but it does not affect accuracy as much as when a plain SS or CM barrel copper fouls.  It will still hold a tight group even with heavy visible copper streaks.  I get about 6 dark green patches out after 100 rounds.    Out of various ammo, it has never shot  worse than 1.9 MOA even with junk ammo.  I can't say that for any other barrel I own, so I'll live with the extra cleaning.    I've got 4 of the CHF barrels, a DD, BFH and two Noveske N4.  None of them shoot consistent groups with various ammo like the ARP will,  but they do clean up easier.  The chrome lined barrels vary greatly from one type of ammo to another.  They range from 1MOA  to  5MOA and the groups tend to open up more as they warm up.  The ARP shoots more consistent hot or cold, but I don't know if that has anything to do with the melonite or not.  

The ARP barrels do have one dimple for the gas block, but I added the second to match the two set screws of the Vltor gas block, plus a cross pin.  

To me these issues are not that big of a deal now that I have worked through them,  but to a first time buyer of a melonite barrel, it is something to be aware of.   If there is any rough spot in the barrel, it is not going to smooth out.  If you need any gunsmithing done such as holes for gas blocks or a pinned flash hider,  most won't touch it due to the wear on the bits and the Jig trying the get the bit to start.  I think ADCO has a warning about this with melonite barrels?   When melonite  wrecks a new cobalt bit using sulfer cutting fluid just trying to drill a .030" deep hole, then it's going to last, probably longer than chrome lined.  For the price, I have yet to find a barrel that will touch the ARP, my biggest complaint is they sell out fast and are never in stock when I get the urge to buy another one.

No complaints from mine

I received a VooDoo Innovations barrel that came extremely dirty.  It was purchased the last Black Friday sale from Elite Tact.  It took hours to clean, even after letting it soak over night several times.  A very dark brown thick crude was coming out of it.  There was no copper fouling.

My two other VooDoo barrels came clean.  Just a couple patches through them and they looked spotless.

I dunno, I do not have these issues.  We did wear out a drill bit after 3 melonite barrels.  Copper, I do not have any issues with this.   I do not get multiple green patches nor do my barrels require excessive cleaning.  I get great accuracy either way, copper solvent or not.  I would leave the copper if your accuracy is not affected.   I think I would contact ARP, especially with the excessive cleaning.  One of the selling points is easier to clean.  I would suggest that the melonite lasting longer than chrome might be a stretch.  That is based on what real world feedback there is.  Good luck with your barrel, but all of your cleaning whoa's are certainly atypical of an ARP or even other nitrided barrels, at least from what I have seen.  

 

I took my Krieger barreled M25 out this weekend. The loads it used to like it no longer does, and some of the loads it didn't like before shoot a lot better. Looks like I'll have to get new load data.

It cleans extremely quickly with minimal fouling and pulling a patch through it feels butter smooth. Of course, this is a krieger barrel with about 1200 rounds through it prior to melonite so any tool marks will have been smoothed out by now.

No issues with my CMMG nitride barrel.  Very smooth bore.  No copper fouling issues (no more than with other barrels), and I've been working up loads for the solid copper Barnes 55 and 62 grain TSX bullets in that rifle.  I also agree that using copper solvent is not necessary unless accuracy declines.  I do start load development with a "clean" bore followed by a couple fouling shots, but "clean" has meant a few patches of ordinary gen 2 Hoppes and a dry patch.  I think most barrels, including nitride, shoot better for me if the deepest layer of carbon is left in place.

I do agree that for inexplicable reasons my barrel shoots M855 (at least the current LC lot I have) much better than is typically reported.

I've been testing and working up true target ammo with Berger bullets and with a 6-24x50 scope in an alternate QD mount to try to find the absolute accuracy limit of the barrel.  I've just about concluded that 1.2 MOA is it without cherry picking. But not bad for a barrel I paid $160 for, if I recall.

Tell us more about the Krieger barrel and who did the nitride.  I have one Kreiger on a target bolt gun that shoots better than I can.  I've been looking at getting a Lilja 1:8 Recon barrel and possible nitride treatment.  I'm just a little reluctant to have a finished AR barrel with attached extension treated unless the company has experience with the issue.

It seems as though there are three different considerations that are being combined or at least not distinguished from one another, resulting in what might appear to be contradictory results.

One is the barrel itself, meaning the metal. Another is the treatment, in this case pretty much either chrome or melonite (salt bath nitride). The third is the method of manufacture, CHF on one hand and drill and rifled (by either button or broach method).

Stainless steel is softer than Chrome Moly. That is why custom barrel makers like to use it. It is easier to drill and rifle. It will also polish up prettier because of the chrome content. We are like crows and are mesmerized by shiny stuff.

Next the treatment. Chrome is another metal which is a added layer to the barrel metal.  A barrel that is chrome lined will be inherently smoother as the chrome will fill the voids in the surface as snow does as it blows across the ground. It also makes the bore smaller so the bore must be initially oversized to account for this.

Nitrocarburizing, commonly called Meloniting is a treatment that changes the molecular structure of the barrel metal. It does not increase the dimension of the barrel metal.

Melonite makes the barrel metal considerably harder, typically Rockwell 64 and while chrome can be as hard as Rockwell 80 when it is applied to a barrel it is typically RHC of 50 to 55.

And thirdly the manufactuing method. The bore of a CHF barrel is going to be inherently very smooth compared to a drilled and rifled barrel due to the nature of the process. You could chrome it or melonite it either one and it would be very smooth. The chrome barrel would probably be smoother.

The observation that a button or broach rifled barrel which is then melonited will suffer from copper fouling, especially in comparison to a chrome lined barrel, makes sense. Unless, as ARS556 suggested, the barrel is hand lapped or broken in, which is simply shooting the barrel smooth and accomplishes the same thing as lapping, after rifling, it would be expected to copper foul. And because of the considerable hardness imparted to it by Meloniting, not likely to get better. At least not for the first 10,000 rounds or so. It would eventually wear the high spots down and then still likely show copper fouling since those spots would then be bare metal and not have the lubricity of the melonited parts of the barrel. Copper is so much softer that its hardness is on a scale (Brinell) that does not even show up on the Rockwell C scale so a barrel has to be pretty smooth and have good lubricity not to scrape copper off the bullet. There will still likely be some due to engraving of the rifling but that is another discussion altogether.

If we were to compare a bare CHF barrel to a bare button rifled barrel that had not been lapped and not been chromed or melonited, the button rifled barrel would show more copper fouling than the CHF barrel.

If we chrome both of them they would probably show a similar lack of copper fouling. The chrome would cover the roughness of the button rifled barrel although the CF barrel might show less copper fouling.

If we Melonited both of them the button rifled barrel would show decidedly more copper fouling that the CHF barrel.

If we lapped the button rifled barrel until it was as smooth as the CHF barrel and then either chromed both or Melonited both, they would show as similar lack of copper fouling.

If we Melonited one CHF barrel and chromed another CHF barrel, the Melonited barrel would be expected to show less copper fouling since the Melonite has better lubricity than chrome although the chrome might have an advantage because it fills the voids. It would be tiny either way.

I am looking at this stuff because I am trying to talk myself into buying a custom barrel. I can't find what I am looking for in an 'off the shelf' configuration. It seems like to only way to get what I want is to have a made to order barrel, which means that I can't get a CHF which I would really like. Thanks to ARS556 I can avoid the mistake of not having it lapped before being Melonited. Thanks!!!!!!!

If I have missed anything. please let me know.

Maybe all the posts before Nov 2014 discussing most of this.  Your points are good ones that have been brought up previously but not in this thread.  Sorry, mostly meant in humor.  These are some of the reasons why I have suggested getting in touch with ARP for the copper fouling offender.  The ARP barrels shouldn't foul like that.  Mine don't.  

Another thing I would add is before you decide on a barrel, you should first set an accuracy goal, at what range and with what ammo?  That may determine what
the barrel life is really going to be before you exceed the accuracy requirement.  A good chrome lined barrel can do MOA but usually only with one cherry picked load.  Most off the shelf non match grade ammo will be in the 3 to 5 MOA range, with match grade averaging somewhere under 2MOA but usually not making it down to 1MOA. 40gr to 50gr varmint tipped loads can shoot at 1MOA in many Chrome lined bores.
These are averages over time and not the best or worst the barrel may do on a certain day.  Chrome lined barrels are just not as consistent, they can shoot great groups now and then, but they tend to vary more even with the same load.

A melonite barrel shoots more like a SS barrel in accuracy but with longer life.

Lets say I set a 2MOA at 200 yards average accuracy goal with Black Hills 77gr as the point when I replace my barrel.  
At 1200 rounds my melonite ARP 16" SOCOM barrel is averaging 1.02MOA with this load.
At 100 rounds my Noveske 16" N4 is averaging 1.56MOA with this load.
At 50 rounds my CLE Douglas SS 16" Recon is averaging 1.1MOA with this load.
At 100 rounds my BCM BFH 16" Midlength is averaging 1.45MOA with this load.

The Melonite appears to have the advantage for now and after 1200 rounds it still shoots with the new SS Compass Lake.  The Chrome Lined barrels start out with a 1/2 MOA disadvantge.  The question is, how many rounds before they exceed 2 MOA with this load?  
And with regular off the shelf ammo like XM855 the Melonite and SS barrel start out with a 1.5 to 2MOA advantage over chrome lined.

This is untrue. Barrel QUALITY is is far larger a determiner of accuracy then coating. A CL knights sr25 or FN barrel SPR A1 is fantastically accurate, and melonite Sig 556 barrels have been notoriously less then base AR15 accurate.

If his data is accurate, the post is not urine. Glad you withdrew that from the post.  The data is the data.  None of his barrels are junk and most are quite highly respected.  I agree that you can't make a silk purse out of a sow's ear by nitriding an inaccurate barrel, but a good QPQ SN treatment of an accurate barrel will not degrade accuracy.  That is why bolt gun benchrest shooters at the national level are seeing longer barrel life on their match grade stainless barrels after QPQ SN treatment with no degrading of accuracy.  However, it appears that the molecular properties of the stainless do not allow the same degree of corrosion protection after nitriding as with a nitrided 4140 and 4150 barrel steel.  The benchrest guys probably don't get particularly concerned about that.

From what I understand of the corrosion issue, the nitrided stainless steel is less corrosion resistance than nitrided carbon steel, but still far more resistant than untreated stainless.

WOW, you have some real blanket statements there.  Maybe you been reading to much?  Which Melonite barrels?  Which stainless barrels?  Which chrome lined barrels?  Which off the shelf non match ammo?  Your statements about chrome lined barrels are false!  Since you don't designate and blanketly state chrome lined barrels being inconsistent, then they are simply false.  My FN barrels are extremely consistent.  I have been around a couple Daniel Defense and they were consistent.  A couple of Green Mountain samples were quite good also.  Then you are all over the place with CL shooting MOA with 1 cherry picked load going on to say  varmint tipped can shoot moa in many CL ......  So I have to surmise maybe you been reading a bit too much and not shooting enough?   If you care to tighten up your statements as tight as you suggest your groups are, we can talk about it.  

 






 

I have an 18" ARP, a 16" CMMG, and a 16" 7.62x39 Tactical Ambush,,, all have been great thus far.

I also use nitrided BCGs and gas tubes, makes for easy cleaning.

True about sample size.  Samples of one are what is called "anecdotal evidence" which is better than nothing, but not scientifically valid.  But if your barrel is a good one the evidence is 100% valid, but only for you.

We need larger samples of very closely similar barrels over very long periods of time to address the QPQ SN barrel life issue.  An accurate barrel or an inaccurate one is, indeed, primarily dependent on the skill, equipment and quality control of the maker.  There will be outliers, but modern equipment and methods usually produce reliable and repeatable data from relatively small samples, but not a sample of one.  It may be the outlier in either direction.

I've been leery of doing gas tubes since it's going to be VERY difficult to clean all the salts out of them afterwards.

If you have CACs you can look at some of the testing done by DoD on the subject on DTIC.  Much of the info is proprietary so you cannot really quote from it though.

What is CACs? I think you need more acronyms in your post, sir.

Common Access Card, the new ID cards that have PKI certs on them and allow access to numerous unclass gov websites that may contain restricted but unclassified data.

FWIW, I have used several nitrided gas tubes lately.  The ones I have purchased are only a dollar more.  I have no idea if they are useful or if they are snake oil.  My only point is they work.  The brands have been Kies and Spikes.  They have all worked and been in spec.  

 

My WMD tube was plugged with salt. They told me the best way to clean it is an ultrasonic cleaner, it's what they use and gets it 100% clean.
Next choice was to soak in parts cleaner and use air hose.

I got one filled from Spike's...they sent me a new one for free.

Why is that?  I thought generally, salts were washed out with water, though I have never heard of salt as an issue in smokeless, except perhaps primer residue.

It is the salt left in the tube from the salt bath nitride process during manufacturing.

It takes some real scrubbing to get it out of barrels.

I'm gonna try the ultrasonic trick on the next batch of barrels, see how that turns out.

Let us know how that works out.
Wish I had an US cleaner big enough for rifle barrels. I use it on pistol barrels, slides, frames and bolt carrier groups. Saves a lot of time.

Based on your response, I am not entirely convinced that you understand the point I was making. The statement that a melonite barrel shoots more like a SS barrel is inaccurate. The quality of the blank and finishing is far more important then the barrel treatment. Melinite barrels aren't always more accurate then chrome, this is a fact, not an opinion. Melinite barrels aren't even always ACCURATE.

Good barrel is a good barrel, bad barrels are bad barrels. Doesn't matter what they're coated with.

This may not apply to .223/5.56 bbls.

I'm doing a long term personal study of 300BLK bbl wear (throat erosion), comparing different bbl steels and treatments.  I keep track of jacketed rounds fired and the throat erosion.  No extended rapid fire; fire 5 shots and let the bbl cool to ambient temp.  Hope I live long enough to complete it!  I have 4140, 41V50, plain, nitrided, and chrome lined.  I have 8 bbls.  So far, I've fired around 14,000 rounds.  Stainless steel too.

So far, plain 4140 wears the fastest, which makes sense, but I am not implying that 4140 is wearing fast in and of itself.  Chrome lined 41V50 wears the slowest, with nitrided in between those 2 extremes.  I estimate, based on results so far, that nitrided will give 1/3rd more life than plain.  Chrome lined will give 1/2 more life than plain.   I do have a 4140 chrome lined bbl on order to see if it wears faster than chrome lined 41V50.   Again, this is 300BLK.  I've started measuring .223/5.56 throat wear but have too little of data so far.  I do have a 10th bbl coming and may shoot it more rapidly, say 10 rounds before cooling, to see how it compares.  Except for a hand lapped bbl, all Blackout bbls exhibited the same wear pattern:  Rapid for the first 30-100 rounds followed by a LONG period of very slow wear.  I suspect the rapid wear at first was simply the removing of burrs left from the forming of the rifling.  

A Daniel Defense 41V50 nitrided 16" bbl is the most accurate, yet a Daniel Defense 10.3" 41V50 nitrided is of average accuracy.

The 26 Nosler is better candidate to test these things.

We must stop using the word "coated" and nitride in the same sentence.  It is not a coating.  It is a penetrating molecular hardening of the steel, itself, that preserves the original machining contours of the steel.  This means that rifling is dimensionally undisturbed.  Chrome lining is a plating on top of the steel.  Done properly, the final result of chrome lining can have only very minor variations in thickness.  Yet, the potential for variation is there and adds an additional variable not present in either unplated steels (whether 4140 or 4150) or stainless.  Nitride treatment of such barrels, including stainless, leaves the dimensions unaltered.

Do not separate and isolate the method of hardening the bore from the inherent quality of the barrel.  These concepts must be viewed in terms of their cumulative impact.  All comparisons of bore hardening must begin with barrels of equal quality.  That is the only way to make valid comparisons.  Only if we begin with equal quality barrels can we remove the effect of barrel manufacturing from the equation and finally isolate on nitride vs. chrome lining when attempting to compare accuracy and ultimate practical barrel life.

This difficulty is the primary reason we do not yet have reliable data on barrel life comparisons between the two treatments.  Sample size must be much larger than simple comparisons of individual and dissimilar barrels.  The cost of equipment, (many barrels of each type) and the many, many thousands of rounds of ammo, perhaps a million rounds all together, is staggering.  No company is likely to want to make that investment.  The DoD might, at some point.  They did conduct tests on Nitride treated heavy truck axles, but suspended the tests when they realized they (at Ohio State University engineering labs under a DoD grant) were using single bath treatment rather than QPQ SN, the later having  much more "slippery"  coefficient of friction.  I have been unable to determine if they changed the protocol and resumed testing.  I doubt that data would translate to rifle barrel life.

Sooner or later good, reliable data will emerge.  It will probably come in the form of retrospective analysis of combined small group studies, trying to filter out  variations in other dissimilar factors.  This will take time.

In the interim, we need to keep up the evaluation process and share our anecdotal data.  Enough has emerged to establish these points:

1.  QPQ SN provides superior corrosion protection to any other currently available commercial barrel material.  On the order of 10x longer salt water immersion compared to hard chrome.

2.  QPQ SN provides an extremely scratch and abrasion resistant surface, far more than other barrel steels.  Try to scratch one of these barrels.

3.  QPQ SN provides these protective qualities to the entire treated surface and not merely the bore.

4.  QPQ SN treatment does not meaningfully alter the pre-treatment dimensions of the product, leaving such things as a rifle bore dimensionally the same.  Chrome lining may introduce thickness variations.

5.  QPQ SN treatment  creates a very hard surface.  The Rockwell hardness scale testing demonstrates that differences in treatment process and substrate steel composition produce some meaningful variations in hardness, ranging from slightly below hard chrome to slightly above hard chrome.  These variations will affect comparisons and control for Rockwell hardness should be accounted for in making comparisons.

6. The QPQ SN process can be performed in more than one way, and variations in technique, equipment and processing skill can produce varying results.  Only a few US companies have the capability to produce uniformly high quality results.  Not all "nitride" is the same.

7. QPQ SN treatment involves use of temperatures at certain stages of the process which are very close to the temperature which would cause certain steels to lose their temper.  Very precise and constant temperature monitoring and control is necessary.  Poor processing and QC could alter the properties of the barrel substrate in undesirable ways.

8.  Assembled products, such as AR barrels and barrel extensions, can have the assembly fasteners lose their required torque during the heat up and cool down phases of the process unless special processes are employed or the parts treated prior to assembly.  Reported cases of ruined barrels due to loosening of barrel extensions after treatment, suggest that treatment of finished and assembled AR barrels should be avoided or used only by companies highly skilled in the special techniques needed to avoid the problem.

9.  QPQ SN treated surfaces are extremely unforgiving to machining after treatment.  Tool bits, especially those moving laterly across a treated surface, such as milling operations or lateral reaming, dull out quickly.  This frustrates such machining processes as chambering a barrel after treatment.  Most machining, including final machining must be done prior to treatment.

There may be other properties that are well enough established to be considered as truth.  

Taking all of this into consideration, the benefits of high quality QPQ SN treatment of a good barrel weigh heavily in its favor with the exception of unknown ultimate practical barrel life compared to chrome lining of an otherwise equal quality barrel.  Only time and expenditure of huge sums of money will answer that question.

And also of extreme importance, while the QPQ SN process is a good process, NOT ALL NITRIDED BARRELS ARE QPQ. Thus causing a major variance in quality of treatment.  And while I agree with most points above.  I do not yet believe  nor am I convinced a similar quality QPQ barrel will outlast a hard chrome barrel.   No definitives in that statement just my beliefs.  I do think based on evidence and "projections" it greatly increases inline barrel life. No question QPQ is more corrosion resistance.  

which version, Q or QPQ?


 

EDIT freaking autocorrect, that should have said unlined in inline

So, if I sent one of my SS barrels to WMD for SN, would it turn it black?  I am just curious.  I have considered this.

I am just about to by my first SN barrel.  I want to get in on this and start learning what all the fuss is about. I think I have decide on the 13.7 from Weapons Outfitters.

It will take me forever to get a high round count, just because I have several others.  My son is really getting in to it, so he will help

Yes, it will come back black.  I've seen a couple bench rest bolt gun stainless barrels done that way.  They were a deep satin black.  Quite striking, yet still understated.  A little different than my AR barrel, but the polishing phase may differ and the substrate metal obviously differs.

Let us know how it turns out. And how it performs.  A before and after photo would be nice.

I know BAT tactical actions are fully nitrided, and Stiller touts their bolt as being nitrided, but does anyone know if Stiller nitrides their TAC actions as well?

I hope to find out someday, but I'm now 66 years old.  I "got into" the 300BLK shortly after it was introduced.  It's a fun and cheap to shoot (I have lots of 30 cal bullets on hand) (I also hunt with it) low recoil cartridge.  I had read stuff similar to "it will last 30,000+ rounds" (due to the small amount of powder vs bore size) or don't bother to measure wear...it will last forever.  Since I had the tools on hand and had been doing it for 30-06 and .308, I decided to find out about the Blackout.  Then it morphed into comparing the various 300BLK bbl types as more type of bbls were introduced into the market.  Then I found a .223 throat erosion gage and decided to monitor those bbls too.  

Prior personal experience with the military standard of 1" of throat wear = a worn out bbl and finding that to be true, at least in 30-06 and 5.56 for military combat accuracy, lead me to the (not yet proven by me) possible theory that a 300BLK bbl with the throat worn 1" will equal a worn out bbl.  My Blackout bbls are no where near that amount of wear yet, and the accuracy is unchanged.  Extrapolating my data so far and ASSUMING THAT THE BBL WEAR WILL CONTINUE AT THE SAME RATE up until the throat has worn 1" after the break in period of 30-100 rounds, 300BLK bbls will last ~11-16 thousand rounds, depending upon the bbl steel and treatment, if any, when shooting jacketed or plated bullets at a slow rate of fire.  That's no more than a .223 bbl would possibly last.    My fun "job" in retirement is to continue shooting and monitoring and see what happens.  

FWIW, from my experience, cast bullets give about 3 times the bbl life of jacketed bullets in rifles (cast bullets loaded hot enough to function the action).  Plated bullets wear the bbl as much as jacketed bullets in rifles.