Nickel guns typically comprised about 10% of the production run of S&W models offering that finish back in the days of blue steel and walnut. I was a stocking S&W dealer when I owned a gun shop during the '70s and '80s, and my discussions with S&W (factory and reps) always came out to that 10% figure. Thus, they are more infrequently encountered than blue guns, as they were produced in much lower numbers. As to care, don't soak them in Hoppes No, 9 (or other ammonia-containing solvent) and leave it on for an extended period, flaking may ensue. I always used Hoppe's, but got it out of the bore and cylinders completely, and used a good oil on interior and exterior surfaces. Nowadays, CLP is my cleaning solvent of choice on nickel guns (Hoppe's Elite is also excellent, without potential damage to the finish). If the finish clouds up, a light polishing with Mother's Mag polish or Flitz (the metal polish, not the fly spray) will bring it right back to life. Keep the nickel protected with a light coat of oil or, better, fine paste wax (Renaissance Wax is best, Johnson's Paste Wax or a non-abrasive Carnauba wax is also very good) - just make sure it contains no abrasives (i.e.: cleaner-wax). Enjoy that 15, they are great shooting guns, and a lot of fun.