[ghostguy6]

Originally Posted by 260 Rem

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?

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.