Some members here have used Bob Cogan of Accurate Plating to do their hard chrome work.
http://www.apwcogan.comHere is Cogan's comparison of nickel and hard chrome, but I have never heard a complaint of the Robar products:
"PLATED FINISH: NICKEL PLATING:
Nickel Plating, has been extensively used in the firearm’s industry for close to 100 years. Nickel finishes have a slight yellow cast to them and this coloring gives Nickel a softer appearance when applied to firearms. The only time we recommend Nickel over a Chrome Finish is to do restoration on older firearms, or when a firearm is so heavily pitted from neglect that full flaw removal would create a dangerous firearm.
Matte Nickel Finishes do not show flaws like Chrome does because of softer coloring. Also, Nickel Plating solutions have chemicals in them that enhances the ability of the plating to fill in and fully cover the flaws that cannot be removed. Nickel Plated Finishes, in general, run about a 45 R.C.
This is as hard as most of the parts in firearms manufacturing, but way off of the standard Hard Chrome at 65 R.C. Also, Nickel can tarnish, or stain like silver. Even some cleaning solvents can damage Nickel Finishes. Chrome, on the other hand, will not change its appearance unless attached by certain strong acids, or bases. Also, Nickel is more prone to show wear due to the lower hardness of the deposit, similar to Stainless Steel Firearms. Nickel and Chrome Finishes cost the same at AP&W. So unless there is special reason to choose Nickel, Chrome would be the better choice. Salt spray ratings are about the same…100+ hours.
Note: Bright Nickel solutions, due to their chemical make, create a more brittle and less ductile deposit on the base metal. This can cause the deposit to actually blow off, or crack where high pressure gas from the cartridge igniting come into direct contact with the plating. This problem mainly occurs with magnum handgun cartridges. AP&W uses a Semi-Bright Nickel solution that can be maintained with low levels of brighteners. This allows for a much less brittle and highly ductile deposit. We have used our tank to base coat magnum high power rifles and have not experienced any separation at the muzzles."