I can't give a specific cite to back this up, but when the gun in question would have been made Colt used the electroless nickel process on nickel guns. EN is applied directly to the steel without copper plating.
Again, if the gun has been replated, all bets are off and the gun likely does have copper. If the gun has not been plated, it has not.
BTW, when I regularly carried a nickel Detective Special I cleaned it with Hoppe's no. 9. I still use that(or Ballistol) to clean it when I shoot it. I am hard pressed to see any difference in the finish today as compared to the photographs I took when I first bought it.
Again, if the gun has been replated, all bets are off and the gun likely does have copper. If the gun has not been plated, it has not.
BTW, when I regularly carried a nickel Detective Special I cleaned it with Hoppe's no. 9. I still use that(or Ballistol) to clean it when I shoot it. I am hard pressed to see any difference in the finish today as compared to the photographs I took when I first bought it.