Nitrided stainless?

[Cold/Bore]

I have no reason to doubt anyone’s experience with their nitrided SS barrels being accurate/durable but most of the personal experience being used as evidence of accuracy/durability of these treated barrels are sample sizes of one. This is not enough to convince me of the benefits of a nitrided SS barrel. Not that I oppose the idea of a more durable and accurate barrel. I would be more inclined to listening to industry professionals like Todd.K who work with far larger sample sizes.

[MegademiC]

What is the appeal of nitrided stainless? If high volume, is it more durable than CL?
If not, is it more accurate, corrosion resistant or durable than nitrided cmv?

[5.56 Bonded SP]

Little off topic but...

I have a nitride 4150 CrMoV barrel that has shot multiple ~ .7'' five shot groups with hand loads at 100 yards. I don't think I am physically capable of shooting better without a mechanical rest, and I don't think my handloading equipment would be able to produce ammo that shot better either.
I'll see if I can find one of the targets later tonight. Barrel is from Areo, 18'' rifle length.

OP do you handload?

[dlraymond30]

No I do not handload yet. I have a nitrided BA 16" Hanson Profile .625" that has shot .6" groups with factory PPU 75gr and .77" with Federal Gold Medal 77 gr SMKs.
I also have an 18" SS BA Rifle Length "Ops 12" barrel that I HAVE NOT shot yet because I have not had enough $ to purchase a decent variable powered optic but what got me to buy it was having a chance to group another shooters build and could not believe what it was shooting with Black Hills mk262! Measured with a ruler it was ~1/3" best 3 shot group (yes I was doing "internet commando" grouping) and I had zero experience group shooting with an AR so, needless to say, I was impressed! Can't wait to get an optic to finally start running mine!
BTW, I actually did the proper "break in" procedure on my 16" nitrided Hanson barrel mentioned above and I was getting those amazing groups... Hell, with factory Winchester 45gr (yes, 45gr out of a 1/7) at 54 yards with and unmagnified Holosun 403A from prone using my range bag as a front rest and a bag of rice as the rear, I got a 1/3 inch group!!!!!! Can you believe that? I was literally giddy!!!!

-Darrin

[snaggletooth]

I remember reading that the way the barrel is Nitrided can make a difference. As the different types to "Nitride" a barrel can bring to different temperatures. Such as a salt bath, which is what QPQ (quench polish quench) can bring a barrel into a temperature range where it can adversely affect the characteristics of that type of metal for the barrel. Generally speaking, you do not want to bring stainless above a certain temp (it differs depending on the composition of the metal. Often why most people say that nitriding generally benefits high carbon steels, is because it is more resilient to the heat/ able to have more hardness stability in that high heat that QPQ nitriding introduces to the metal.

There is also gas nitriding, and also plasma nitriding. For stainless I remember reading that plasma nitriding was the best way to apply onto the metal, as it is a lower temp allowing for the metal to not change its properties.

I also remember reading that the purpose of nitride originally was to enhance the mechanical application of a metal, ie make it a harder surface. So the properties of stainless barrels being easier to machine and then nitriding would allow for that barrel to maintain its accuracy for a longer period that if it were untreated. The fact about increasing corrosion resistance sometimes applies sometimes it is adversely affected. I don't know if anyone remembers the stainless smith and wesson M&P slides that were rusting, those were nitrided (however, the wrong application for applying the nitride properties (someone correct if I am wrong) was used). I believe if the M&P slides had used something that didn't change the properties it would have had better results with the corrosion resistance issue.

I have had several stainless barrels that I have sent out to be nitrided. I assembled them in uppers, shot them to break in and have the barrel settle down. Once I believe I got the barrel to be at a point where the little burs and imperfections have worked itself out and the accuracy just hits the right spot for me. I take the upper apart and send them to be plasma nitrided. Just look up plasma nitriding or ion nitriding and you will find a bunch of places that can do that for you. It isn't cheap, but I thought "what the hell?" It wouldn't hurt to try

[vicious_cb]

What is the appeal of nitrided stainless? If high volume, is it more durable than CL?
If not, is it more accurate, corrosion resistant or durable than nitrided cmv?

It shouldnt be since a barrel's overall toughness is based on the substrate material rather than the coating. What kills a barrel is throat erosion. The coating or surface treatment wont last long in the throat so the base steel will start to matter sooner rather than later. CMV handles heat much better than stainless so there is no reason to use stainless in a high volume application whether its treated or coated or not. Correct me if Im wrong Todd K.

As far as corrosion goes 416R has pretty shitty corrosion resistance anyway, I found that out the hard way after leaving a stainless steel barreled AR in my trunk overnight the condensation on the barrel was enough to cause rust spots to form.

[Todd.K]

CMV handles heat much better than stainless so there is no reason to use stainless in a high volume application whether its treated or coated or not.

As far as corrosion goes 416R has pretty shitty corrosion resistance anyway, I found that out the hard way after leaving a stainless steel barreled AR in my trunk overnight the condensation on the barrel was enough to cause rust spots to form.

Correct. Stainless softens at a lower temperature and softer metal erodes faster.

416 is stainless enough for most uses. It's not pretty when you get some surface rust but it takes a long time for it to be anything but cosmetic. And the bore is a polished finish and so more corrosion resistant than a rough outer finish. All my stainless barrels are KG or polished outside.

I don't have any large number comparison data, sorry.

So I'm clear, I don't have a problem with nitrided SS barrels. Given them not being run too hot, they should have a somewhat longer accurate lifespan, at somewhat less accuracy than uncoated SS barrels. To quantify those "somewhat's" is where it gets harder.

Besides the cost of ordering 4150 CMV in quantity, the better product for this in between SS and CL, based on what I know, would be a 4150 match barrel with nitride.

[dlraymond30]

I have 5 m&p pistols and none of them have ever had any issues rusting and i have had them in extreme conditions because i love them but i do believe you are correct with some of the earlier ones.

everyone, thanks so much for all the help and info on this topic!