I am wondering who does the best nitriding work on barrels in the industry.

That's a tough question as there is a lot of before and after depending on the project...

Nitride isn't even a specific term as there are numerous processes that functional do that same thing...all with varrying degrees of success in the gun world.

There are deep debates about nitriding certain types of barrels, certain steels, whether you can or can't with certain rifling designs, after X # of rounds, whether it will affect the heat treat of the steel, and on and on...

If you want to do a precision rifle barrel, the best POC is Dave Tooley.  He has done it successfully on precision rifles.  If it's for an AR...I wouldn't bother.  Either way, even the best precision rifle smiths have opined that it isn't usually worth it as it won't make the barrel more accurate and won't address the primary wear point on a precision rifle barrel, the throat, as it can't alter the melting point of the steel and fire checking is what kills the throat.

It will add corrosion resistance and make it resist cleaning rod damage...but that's not likely a problem.

Lookup "Bamban nitriding". You might want to sign up for usrifleteams.com. (I hated having another forum account, but great resource)

Nez makes a few barrels for the TSRA service rifle teams and had several nitrided. I think one guy's nitrided Shilen is over 7,000rds with half the erosion of an untreated Krieger.

Nitriding is good for gas blocks, gas tubes, bolts and carriers.  Not good for barrels.

More detail please.

Tech Nickel - Benton Harbor, MI does this kind of work. Jagerwerks uses them for Glock slides. I just sent three Lothar-Walther barrels to them for salt bath nitriding.

Superior barrels had my vote, but they're out of business.

GunBlack in New York does Nitriding and Black Oxide.  They do small batches.  Not sure about single items.