CrN is not very electrically conductive, so you cannot electroplate it. NP3 is autocatalytic - not deposited by electrolysis - so there is a chance it will work. But CrN does not offer much 'tooth' to attach the nickel-phosphorous to, so it may flake off. You can electroplate to the vapor deposited carbides because they are sufficiently conductive, but not autocatalytically plate them. The vapor deposited carbides offer about the same 'tooth' as CrN vapor deposited coatings.
Why don't you contact Ruger and see if they will sell you a bare stainless cylinder? All they would be doing is bypassing the coating operation. Their parts people are helpful and the cost would be much lower.
I emailed Ruger about this and the sights issue [supposedly a lot of the aftermarket sights don't have the same POI with the 327 Federal] and they just replied they don't sell any night or fiber optic sights that work with the 327 Federal. Maybe I'll ask them solely about this at a later time.
Bring it to me and I'll blast it and cerakote the barrel in stainless cerakote. $30 which is a pretty cheap option that will last a lifetime.
No clause in the constitution could by any rule of construction be conceived to give congress a power to disarm the people. Such a flagitious attempt could only be made under some general pretence by a state legislature. But if in any blind pursuit of inordinate power, either should attempt it, this amendment may be appealed to as a restraint on both.
William Rawle - offered the position of the first Attorney General of the United States, by President Washington