Faxon claims that Nitride is technically more accurate than Chrome Lined because the former is just changing the chemical properties of the steel, while the latter is actually adding material to the bore. Faxon as a company is more into Nitride than anything else, so take it with a grain of salt. They'd also be the first to say, "It depends."

To be frank, however, none of that matters when you're shoving minute-of-man steel case down the bore - the ammo is way less accurate than the barrel. And if you're really doing long-range precision rifle marksmanship where fractions-of-a-minute matters, then there are far more important factors to worry about for your barrel than the treatment used at the end.