Will any thing replace chrome lined barrels? Any new technology on the horizon?

Stainless Carbon fiber wrapped. Just read an article in some tactical type magazine, using this technology they had made a full size AR 308, Mega, that weighed the same as a 223 AR carbine.

It was pretty acurate, one hole/clover leaf groups at 100 yards

I wouldn't say its a replacement for chrome lined, it was more of a replacement for the heavy stainless match barrels.
 
Nitriding seemed to be the replacement, I remember people got really fussy at H&K MR223 and MR556 over the fact it does not use chrome line barrel (nitride instead)
 
I think nitriding is the future. There are several types of nitriding, though...the type that killed some 58s required more heat soak time IIRC. There are other approaches that don't have the same drawbacks.

I think that ultimately nitriding will replace chrome lining entirely. I think some types of ferritic nitriding are already measurably superior.
 
TK-Hryciuk said:
Nitriding.
Click to expand...

Winner winner, chicken dinner.

I'll be having ATRS build me a new shorty upper in the not-do-distant future and considering the scarce(r) availability of ready-to-go chromed line factory barrels, mine will most definitely be nitrited. Though it sounds like a compromise, from everyone I've talked too about this process the overwhelming feedback is that it's almost indestructible.

I know that Ian @ Herron Arms has been doing it for a while now; AngryEyeBrows as had a few done by him and he seems quite happy with the results. I’m sure he’ll chime in. There are some companies out there who treat not only their barrel riffling but the whole rig with this stuff.
 
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Nitriding as mentioned.

However, Nickel Boron plating might give it a run for its money, *if* they can figure out how to apply it properly to the interior surface of a barrel, which is appearantly a showstopper at the moment.
 
There are a number of coating that show promise.

However right now in long term durability testing I don't think Chrome can be beat for small arm barrels.

Nitriding does offer some advantages - however it does not bond as well to the substruct steel as Chrome, thus it can flake over time (and so can chrome).
As I understand it Hk uses Nitriding more for two reasons over chrome - they use CR32 steel barrels, thus the exteriors cannot be Manganese phosphate coated, while the interior and exterior of a barrel can be Nitrided - as well as Europe has clamped down on the use of hexavalent chromes.

Most of the vapor deposition coatings suffer from the ability of the coating to be applied evenly in smaller than .50" ID barrels, however when that nut is cracked, I think that there will be a broad new future for small arms barrels in terms of wear and reliability. Which in turn should allow for higher pressure ammo etc.
 
Thought I’d clear the air a bit on the subject of nitriding……

Just to be clear “nitriding” alone will not sufficiently replace the benefits of chrome plating in rifle/pistol barrels.

Chrome plating has a dual purpose; wear resistance and corrosion resistance. In order to suitably replace this process a replacement must be capable of both characteristics.

Nitriding is the thermal diffusion of atomic nitrogen into the surface of steel which over time generates a hardened (primarily) subsurface layer comprised of a compound (white) layer and a diffusion case. This harden layer (not a coating) provides a lower coefficient of friction on the surface of a component giving it great wear resistant properties as well as anti-spalling, anti-galling and anti-adhesion properties.

There are essentially four types of nitriding methods available on the market: Ion (Plasma), Salt Bath, Gaseous, and Controlled Gaseous. Each method has its pro’s and con’s depending on different applications. Remember the key here is to identify a suitable process that can replace chrome plating in rifle/pistol barrels.

Ion (Plasma) nitriding works on the basic principle of diffusing nitrogen in the surface of the material by utilizing the part as a cathode and the nitriding vessel as an anode thereby generating an ionic charge around the part which aids in the diffusion of nitrogen into the surface of the steel. This process, for it’s time, worked very well and provided good wear characteristics on components however, there were a few downsides. Part geometry was critical; this method essentially only benefited areas that were visible (line of sight), blind holes, deep bores typically would not be treated and uniformity was not the greatest. As well, it was very difficult (albeit now somewhat better) to control the rate of nitrogen diffusion into the steel. What this meant was that the compound layer produced has a tendency towards brittleness. For this reason many manufactures employed a white layer removal process after nitriding in an effort to still benefit from the diffusion case but minimize the chances of spalling at the surface. As well, there is really no appreciable corrosion enhancement when utilizing this technique.

Salt Bath nitriding/ferritic nitrocarburizing is a process which utilizes molten cyanide salt to achieve nitrogen diffusion into the surface of the steel. This process generates a wear resistant surface with an added benefit of corrosion resistance. This corrosion resistance is achieved by the creation of an oxide layer on the surface of the component after quenching. This oxide layer will be present on the part regardless and if not wanted would have to be mechanically removed after processing. One of the downsides is that parts are subjected to thermal shock when submerged into the process which can lead to part deformation. While uniformity is not bad, it can be very difficult to design a repeatable process which means that from lot to lot there will be variation. Also, the environmental impacts of this process are fairly significant which in turn has driven many providers to discontinue its use here in Canada.

Gaseous nitriding/ferritic nitrocarburizing is a method in which parts are subjected to a nitrogen rich process atmosphere at suitable temperatures which will initiate the diffusion activity. Parts are typically slowly heated to process temperatures by radiant heat under protective atmosphere as to not cause unwanted oxides on the parts. Once parts are heated sufficiently, nitrogen carrier gases are introduced (anhydrous ammonia). This generates a nitrogen rich atmosphere that facilitates the diffusion process. This form of nitriding, being atmospheric, allows the atomic nitrogen to diffuse into all surfaces of a component and is not geometrically dependant. This process provides a very uniform treatment and will not subject the component to thermal shock or harmful oxides. Post process oxidation can also be implemented which will produce a superficial oxide layer that will enhance corrosion resistance. One of the downsides to traditional gaseous nitriding is the lack of control with respect to diffusion rates. This lack of control can lead to oversaturation of nitrogen on the surface of the component which can cause embitterment of the compound layer and cause surface spalling/chipping. As well, repeatability and consistency from batch to batch will vary due to manual control and load configuration.

Controlled Gaseous nitriding/ferritic nitrocarburizing works on the above principles of Gaseous Nitriding with the addition of automated process controls to monitor and adjust process parameters in such way as to ensure control of diffusion rates and compound layer development at the surface. This is done through unique gas analyzers and proprietary calculations that run in a closed loop system to ensure that oversaturation does not occur and the compound layer formed is ductile. Due to the automatic controls and uniformity of the process, lot to lot repeatability is easily achieved. As with gaseous nitriding, an in situ post nitride oxidation stage can be implemented if required to enhance corrosion resistance of the steel as well.

There are a variety of trademarked process out there; Malcomizing, Tenifer, Melonite QPQ, Nitreg-ONC etc. however, fundamentally each can be categorized into one of the four nitriding methods listed above which may or may not suit the application in question.

In order to replace chrome plating in rifle/pistol barrels for civilian applications the process selected in my eyes would have to be capable of achieving the following: generate a uniform ductile compound layer in and around the entire component, allow for in situ controlled oxidation, have minimal effect on dimensional tolerances and most importantly be consistent and repeatable from barrel to barrel. This would provide exceptional wear and corrosion resistance and would be able to replace the need for traditional chrome plating and subsequent phosphate coating.

….my $0.02
 
If we had a post of the year contest, I'd nominate this. Very well written, and I learned a few things about nitriding.

Steggs said:
Thought I’d clear the air a bit on the subject of nitriding……

Just to be clear “nitriding” alone will not sufficiently replace the benefits of chrome plating in rifle/pistol barrels.

Chrome plating has a dual purpose; wear resistance and corrosion resistance. In order to suitably replace this process a replacement must be capable of both characteristics.

Nitriding is the thermal diffusion of atomic nitrogen into the surface of steel which over time generates a hardened (primarily) subsurface layer comprised of a compound (white) layer and a diffusion case. This harden layer (not a coating) provides a lower coefficient of friction on the surface of a component giving it great wear resistant properties as well as anti-spalling, anti-galling and anti-adhesion properties.

There are essentially four types of nitriding methods available on the market: Ion (Plasma), Salt Bath, Gaseous, and Controlled Gaseous. Each method has its pro’s and con’s depending on different applications. Remember the key here is to identify a suitable process that can replace chrome plating in rifle/pistol barrels.

Ion (Plasma) nitriding works on the basic principle of diffusing nitrogen in the surface of the material by utilizing the part as a cathode and the nitriding vessel as an anode thereby generating an ionic charge around the part which aids in the diffusion of nitrogen into the surface of the steel. This process, for it’s time, worked very well and provided good wear characteristics on components however, there were a few downsides. Part geometry was critical; this method essentially only benefited areas that were visible (line of sight), blind holes, deep bores typically would not be treated and uniformity was not the greatest. As well, it was very difficult (albeit now somewhat better) to control the rate of nitrogen diffusion into the steel. What this meant was that the compound layer produced has a tendency towards brittleness. For this reason many manufactures employed a white layer removal process after nitriding in an effort to still benefit from the diffusion case but minimize the chances of spalling at the surface. As well, there is really no appreciable corrosion enhancement when utilizing this technique.

Salt Bath nitriding/ferritic nitrocarburizing is a process which utilizes molten cyanide salt to achieve nitrogen diffusion into the surface of the steel. This process generates a wear resistant surface with an added benefit of corrosion resistance. This corrosion resistance is achieved by the creation of an oxide layer on the surface of the component after quenching. This oxide layer will be present on the part regardless and if not wanted would have to be mechanically removed after processing. One of the downsides is that parts are subjected to thermal shock when submerged into the process which can lead to part deformation. While uniformity is not bad, it can be very difficult to design a repeatable process which means that from lot to lot there will be variation. Also, the environmental impacts of this process are fairly significant which in turn has driven many providers to discontinue its use here in Canada.

Gaseous nitriding/ferritic nitrocarburizing is a method in which parts are subjected to a nitrogen rich process atmosphere at suitable temperatures which will initiate the diffusion activity. Parts are typically slowly heated to process temperatures by radiant heat under protective atmosphere as to not cause unwanted oxides on the parts. Once parts are heated sufficiently, nitrogen carrier gases are introduced (anhydrous ammonia). This generates a nitrogen rich atmosphere that facilitates the diffusion process. This form of nitriding, being atmospheric, allows the atomic nitrogen to diffuse into all surfaces of a component and is not geometrically dependant. This process provides a very uniform treatment and will not subject the component to thermal shock or harmful oxides. Post process oxidation can also be implemented which will produce a superficial oxide layer that will enhance corrosion resistance. One of the downsides to traditional gaseous nitriding is the lack of control with respect to diffusion rates. This lack of control can lead to oversaturation of nitrogen on the surface of the component which can cause embitterment of the compound layer and cause surface spalling/chipping. As well, repeatability and consistency from batch to batch will vary due to manual control and load configuration.

Controlled Gaseous nitriding/ferritic nitrocarburizing works on the above principles of Gaseous Nitriding with the addition of automated process controls to monitor and adjust process parameters in such way as to ensure control of diffusion rates and compound layer development at the surface. This is done through unique gas analyzers and proprietary calculations that run in a closed loop system to ensure that oversaturation does not occur and the compound layer formed is ductile. Due to the automatic controls and uniformity of the process, lot to lot repeatability is easily achieved. As with gaseous nitriding, an in situ post nitride oxidation stage can be implemented if required to enhance corrosion resistance of the steel as well.

There are a variety of trademarked process out there; Malcomizing, Tenifer, Melonite QPQ, Nitreg-ONC etc. however, fundamentally each can be categorized into one of the four nitriding methods listed above which may or may not suit the application in question.

In order to replace chrome plating in rifle/pistol barrels for civilian applications the process selected in my eyes would have to be capable of achieving the following: generate a uniform ductile compound layer in and around the entire component, allow for in situ controlled oxidation, have minimal effect on dimensional tolerances and most importantly be consistent and repeatable from barrel to barrel. This would provide exceptional wear and corrosion resistance and would be able to replace the need for traditional chrome plating and subsequent phosphate coating.

….my $0.02
Click to expand...
 
I believe that Controlled Gaseous nitriding/ferritic nitrocarburizing is used for Swiss Arms Barrels...consistent and good results.

Rich
 
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