The nickel may be a refinish but you shouldn't conclude that just from the lack of an N on the rear of the cylinder. I have a 3.5 inch 27-2 in nickel (S sn) which also does not have an N on the rear of the cylinder but has a large capital N on the left side of the frame under the stock. Check to see if yours has one there. Nice gun, enjoy.

Jeff
SWCA #1457