It's hard chrome not titanium nitride. I have a RBL-12 32 incher with > 600 rounds through it on sporting courses and some hunting with steel and bismuth. I always scrub the barrels of anything I shoot after 100 rounds on a clays course, using a Brownells heavy duty bronze bore brush to eliminate plastic wad buldup, and the RBL is the ONLY gun I own that shows heavy copper color on the patch (from the scrub brush). From this I conclude the Tuff Bore coating is pretty darn hard.
Chuck and Geno are correct, the titanium nitride (derivative of nitrate per CSMC) used on RBL's is used to create the gold colored protective finish on the triggers and some internal parts. I have heard mixed reviews on how durable it is; my personal take is it depends on the thickness of the TiN coating. Silvers
