Nitriding a Barrel
 

Anybody had a chambered barrel (bore included) nitride treated...results?

Can’t see why it won’t hurt but don’t really see any benefits of it either. Not in this application.
What reason to do you see it benefiting?

Make sure you ask for qpq liquid nitriding.

A friend is having one done as an experiment ... I think most to see if it affects accuracy. If it works, I would consider having a sporter contour done as a rust inhibitor.

If it’s a new build possibly but to tear a rifle down to try it, think I’d be chatting with a couple of builders or further research is needed.

Only tinkering with aftermarket barrels on builds. If it does not have a negative effect on accuracy, it would be interesting to do some assessment regarding throat errosion and resistance to fouling.

I've got an rks barrel that was nitrited, thus far it shows sub 3/4 moa but I only have about 40 rounds through it. I've heard that nitriding can increase break in time as the coating takes a while to break down inside the bore, not sure how reliable that is though. The coating has also not been blown off the muzzle/crown area of the barrel, which with my cerakoted barrel the coating was starting to come off after 20 shots

Thanks for your info 7RM. My understanding is that the break-in needs to be done before the process ... then cleaned completely of copper fouling ... preferably confirmed with a bore scope. If nitrided over, the copper would be near impossible to remove.
I have a couple of sporter contour barrels with a few hundred rounds through them to choose between if I decide to give it a try. I am hoping my friend gets his to the Range within a few weeks.
EDIT: What color did your barrel take?

Copper reacts with nitriding causing pitting

you may get longer barrel life. although with a case hardening thickness of 2 thou i doubt you notice it.

i think you would notice increased cleaning due to a rougher surface than before.

i personally wouldn't because why mess with a good thing? if it was the new big thing everyone would be doing it.

Hmmm...nice to have a friend taking the lead. Buddy did mention it would need some "cleaning up" ... don't know if that would involve polishing in any way. I was unaware the nitrided surface would be rougher. The real test will start once he starts shooting the barrel.
I suppose I could get the results I am looking for to reduce shine/rust in the field by using multicolor sharpies:)

it's used commonly as a replacement for bluing and used frequently used in the machinery world to case harden and inhibit rust formation by holding oil. the process is a form of oxidation not unlike rust.

on a new barrel where you might lapp the bore after treatment i would consider it. then you have case hardening and potentially a very smooth bore.

I will likely eventually have a talk with Thermex ... in a perfect world, it would be nice to nitride the exterior surface and leave the bore, but maybe not possible?

see if they can do it, i bet they can, they're pretty good.

Spoke with my friend this morning... He had a KSA barrel chambered to 6.5 Grendel and nitrided before any rounds fired. Initial cleaning was difficult and he resorted to bore paste to get it nice and smooth. Has shot only two 5 shot fireforming groups that came in mid .3’s.
I have contacted Thermex to see if they have process to do “outside” only but have not yet had a reply.

Is this coating impervious to moisture?

not by itself

If you want to selectively nitride a surface you would have to use gas nitriding. When I worked there they were not set up for that although they may be now. I did a few barrels there but they are a pain to wash the salt out of the bore when its finished. Once that salt solidifies your taking it to a gunsmith to be professionally cleaned and inspected. There are two different salt baths and a light sandblasting between each coat. After the first coat is applied the surface oxides must be removed or the second coat will turn out a bright rust red color. It is impossible to fully remove that oxide from the bore with the sand blaster so you can expect the reddish color in your bore. Also the finish on the outside will vary similar to cold blueing, If you leave it long enough you can get a fairly black surface but there still might be color variances. If left long enough you can expect a surface hardness of 520 to 700 brinell if I remember correctly. There is some microscopic surface pitting when liquid nitriding so I would expect your bore to foul more quickly. Lastly I'm not even sure if they would touch a used barrel because of the risk of copper and lead contamination. All the ones I did were new heavy barrel .338 lapua's but I do know each one was inspected by the armorers for the military so I cant say exactly what had to happen before they could be used.

Ghost —Thanks for sharing your knowledge/experience. Yes, he had quite a time getting the salt out of the bore. Eventually resorted to bore paste. (That experience alone turned me off the idea of trying the bore.). He keeps good records so after some time, should have comment on the nitride effect on the throat (ie: does the hardness decrease the rate of throat erosion?), rate of fouling, group consistency.

Please let me know what your findings are. I always wondered if it was worth it because we would get lots of bolt, action and trigger group parts but few barrels. I started to get the impression that the barrels were some sort of test just based on the ratio. Since these were milspec rifles I thought they would have all been made to the same specs.

If it is not weather impervious then what is the attraction?

Its not 100% corrosion resistant but it helps, its like a heavy duty version of blueing but also surface hardens the steel up to a depth of 0.012"

if they don't i just sent some stuff to hi tech heat treating for gas

Any follow up on results of nitriding the barrel?

I will ask friend for an update next time I see him.

I have seen a barrel that was melenited (sp) it did not preform very well.
The bore fouled badly possibly from the harder finished surface.

Spoke with friend today ... he has not been shooting the barrel much over the past year ... only about 400 rounds to date and no sign of throat erosion... but that would be expected with pretty much any throat shooting a “barrel friendly” cartridge like the Grendel.

Did he mention anything about the barrel fouling?

I didn’t ask about fouling but will.