Phosphate vs nitride finish?

[milemaker13]

Whats the difference here? I think nitride is smooth shiny black while phosphate is rough flat black... is that correct?
I have examples of both. What are the pros and cons of each? It seems phosphate generally costs more on similar parts offered in both finishes...

 

[badkarmamib]

Phosphate is a porous surface, that holds rust-inhibiting grease and oil well, to stave off corrosion. Phosphate is the mil-spec outside barrel treatment. Nitride is essentially case-hardening, a treatment that leaves the surface smooth for ease of cleaning, hard for wear resistance, and also providing for some corrosion resistance (think Glock slides).

 

[milemaker13]

Reading more it seems like I had my thinking backwards? Seems like nitride is the way to go, huh?
I'm guessing the reason phosphate seems pricier is because its coated on the outside and chromed on the inside, whereas nitride is simply heat treated through out.
Does that mean that a nitride barrel negates the need for chrome lining? Seems that is what folks are saying...

 

[badkarmamib]

Yes, nitriding is a substitute for chrome-lining. Better, IMHO. Chrome plating can be applied unevenly, and the bore has to be oversized to begin with, to allow for the thickness of the chrome. Nitriding negates this.

 

[someguy2800]

Not all phosphate or parkerized barrels are going to be chrome lined. I prefer nitride finish just for aesthetic reasons. I haven't had any corrosion issues with nitride barrels either.

 

[Pat Riot]

I agree with Badkarmamib.

I would prefer Nitride over Phosphate.
Just as phosphate holds oils it can also hold dirt and moisture. It’s a good and tough finish but given a choice I would go with Nitride if those were my only 2 options.

 

[md7]

As has been stated, phosphate finish is applied to the exterior of a barrel, whereas the inside will be unlined or chrome lined.

Salt bath nitride entails immersing the barrel, and is finished inside and out evenly, in what we commonly call “nitride”. Tennifer, melonite, armornite, etc. are all trademarked types of nitride in use by Glock, Smith & Wesson, etc.

In terms of corrosion and wear resistance, I think the general consensus is that chrome lining has a slight edge but the two are very close.

From my limited research, the area where chrome lining is most beneficial is when you introduce sustained, full auto fire.

For semi auto only, I’m not really sure one matters too much over the other. I’d be more interested in the barrel itself being properly made than whether it was nitride or phosphate/chromed.

That’s just my .02

 

[Varminterror]

Does that mean that a nitride barrel negates the need for chrome lining?

Is there a need for chrome lining in a civilian semiautomatic firearm?

 

[badkarmamib]

Is there a need for chrome lining in a civilian semiautomatic firearm?

It is supposed to make the barrel somewhat easier to clean. To what extent, I am not sure. If I had it to do all over again, all of my barrels would be nitride. It wasn't very popular when I started, and it isn't worth the cost to change now.

 

[rbernie]

Is there a need for chrome lining in a civilian semiautomatic firearm?

Any firearm that is likely to be subjected to condensing humidity and not rigorously maintained could benefit. I know a lot of folk who would not have a trunk/truck gun without.

 

[boom boom]

Military spec (if it hasn't changed) requires parkerizing the outside and chrome inside the barrel. A lot of barrel manufacturers are going to nitrocarburized barrels inside and out (there are several different ways to apply it). The cheapest AR barrels still seem to be regular chrome-moly steel with parkerized outside finishes.

In the last several years, nitro carburized barrels are barely priced about the chrome-moly ones and now are often significantly cheaper than mil-spec types in popular calibers.

Parkerizing is a demonstrated well developed way to keep the outside of a barrel protected from rust and corrosion as long as grease and oil are applied on a semi-regular basis. I have Parkerized 1917 Rifle barrels from the WWI era that are still in good external shape with little pitting or rust scaling evident. Similarly, chrome protects the insides and I have several Japanese T99 Arisakas with chromed barrels that are quite shiny with little evidence of corrosion despite over seventy years of existence. It works.

But, so does nitrocarburizing--witness how resistant Glocks are and have been demonstrated over time to be resistant to pretty awful conditions and nitrocarburizing protects the interior and exterior of the barrel and even hardens the steel. (Just don't try using your machine tools on these or you will find out just how hard the stuff is).

Of course, plain chrome moly barrels or even carbon steel with bluing that are regularly oiled and taken care of are ok too. I have century old German and Swede Mauser blued barrels that appear pristine inside and quite good outside (some wear on the bluing).

Keep up your rifle and all will serve. Abuse it, and probably nitrocarburizing might hold up the best followed by milspec (absent full auto fire).

In a few instances, you will find some problems with crappy nitrocarburizing where it was not applied correctly. Obviously, avoid these.

 

[Varminterror]

Any firearm that is likely to be subjected to condensing humidity and not rigorously maintained could benefit. I know a lot of folk who would not have a trunk/truck gun without.

I was being facetious. My bad for assuming that would be obvious.

You couldn’t give me a chrome lined barrel for my rifles.

 

[milemaker13]

Is there a need for chrome lining in a civilian semiautomatic firearm?

Well, it would make your bullets go faster... I mean, everybody knows that

 

[ATLDave]

You couldn’t give me a chrome lined barrel for my rifles.

I was just thinking about this the other day. Maybe 10 years ago, "chrome lined" was a big selling point for a lot of buyers of certain categories of rifles. Now, it is widely perceived as being detrimental to accuracy and not justified in terms of durability as other methods have been more widely accepted.

 

[Speedo66]

I think the barrel on my Chinese SKS is chrome lined, figure maybe it's to prevent rust from corrosive ammo?

As far as nitride coatings, I carried a Glock as a service gun for many years, summers in a very sweaty climate. Off duty in an inside the waistband holster. Zero rust on the slide. I don't know what coating Ruger uses, but my first gen LCP slide rusted almost immediately.

 

[dfariswheel]

Phosphating is really what Parkerizing is.
One of the first to offer it in the early 1900's was the Parker Company.
It was originally developed as an undercoat for paint, then was discovered to be an excellent finish for military firearms since it was far more durable then bluing.
Currently it's available as the original Zinc phosphate and the modern military Manganese phosphate.
It can be done in the original gray, black, or at least one service offers WWII gray-green.

It's been used on military and harsh use sporting guns because the coating soaks up and holds oils and it's the oil that prevents rust.
The only possible disadvantage of phosphating is that it builds up on the surface and can't be allowed inside a standard carbon steel barrel.
It also won't work on stainless steel.

Nitride is a method of surface hardening steel and it's very rust resistant and increases barrel life due to the hardness.
It works very well inside barrels and outside as a finish, and can be done to stainless steel.

According to former Customer Service and Custom Shop manager Brent Turchi at Colt, Colt did extensive experiments with nitride processing to find out if it offered anything over hard chrome lining of barrels.
Brent said that Colt's experiments indicated that hard chrome was still superior as a barrel treatment.

My buddy is a long range shooter that uses some HOT 6mm loads and he has his stainless Match barrels nitrided.
He says he's seeing about twice the service life over unprocessed stainless barrels.

Hard chromes advantages are....
It's so hard that barrel life is greatly extended.
The "slick" chrome won't allow carbon or copper fouling to adhere like it does in un-coated barrels. Clean up is much easier and faster.
It's highly corrosion resistant especially to corrosive primed ammo.
Chambering and extraction is greatly enhanced.

One down side is that "usually" (but not always) a hard chrome lined barrel is slightly less accurate. This is only a real issue in accuracy rifles, not in military weapons, or civilian rifles like the AR-15.

So, as a firearms finish nitride is better then phosphate in most applications.
Phosphate is "usually" cheaper then nitride although you can find deals on nitriding of barrels. My buddy gets his done for $40. a barrel.

One caution on having a barrel nitride processed.... The bore MUST be TOTALLY clean or the process will fail.
My buddies processor tells him to fire no more then a just few shots to break in the bore then get it as clean as possible.
Since in a Match stainless steel barrel he's only breaking in the leade in front of the bullet it only takes possibly 5 shots.
There seem to be questions as to whether a used gun barrel can be effectively nitride processed.

 

[Varminterror]

Maybe 10 years ago, "chrome lined" was a big selling point for a lot of buyers of certain categories of rifles.

I remember that resurgence when the prepper trend started running amok and the surplus imports started skyrocketing in prices, and AR’s took hold.

I started with chrome lined barrels when I built my first AR for myself in the late 1990’s - I wasn’t impressed then, so I foolishly even felt a Mini-14 might be a better rifle for 3 gun when we started running around with rifles back then in the Midwest. I built my first precision AR for Service Rifle matches on a stainless steel barrel to replace my Garand in about 2002 and realized how terribly misguided I had been by my mentor-smith in my earlier years who favored chrome lined barrels.

I’ve ground up built over 200 AR’s, and rebarreled about as many more, worked on twice as many. I have built a lot on chrome lined barrels for customers upon their request, but most often, I recommend ardently against it, and really recommend those folks don’t waste money having one built, just buy some bargain barrel rifle or upper and be happy with dismal precision...

 

[Mosin Bubba]

I wouldn't buy something like an SKS without a chromed bore because of corrosive ammo and the huge amount of wear and tear on some of those old guns. My Norinco has wood and metal that looks like the rifle was dragged behind a truck, but it still shoots fine (by SKS standards) because the barrel was protected.

But for brand new guns, there's no need.