Any plating - regardless of manufacture or metal being plated is always subject to peeling. Contamination during the process is one of the major causes of peeling of plating. If there is not a perfect bonding of the platings molecules to the material being plated, it will simply not hold up well.

I believe that Tyrod is correct in stating that S&W did not use Copper first as a base plating and Colt did. I do own a few Colts that do have Copper plating under the Nickel and they were made in the 1960's. Before I realized Ammonia based solvents were no good for them, I used Hoppes 9 many many times for many many years - no plating damage; no plating chipping or flaking. I no longer use Hoppes 9 as the guns are not getting any younger and don't want to chance it since I now know better, but I guess I was lucky in the fact there is no damage.

While I too have seen chipping and flaking on more than a few Nickeled guns (all brands) we really do not know the exact cause (Ammonia, no under plating, poor adhesion due to contaminants, poor temperature control) who knows!

My personal experience with Nickeled guns has been excellent although it is in no way my favorite finish. A properly plated gun in good condition should stand up well for many years. Again - I am NOT advocating using anything with Ammonia in it (no longer use it myself)- just to be on the safe side. S&W's Nickel plating from the 50's through the 80's is in my opinion very good quality plating, as is Colt's.