You might find that a VERY SMALL scratch mark on the outside rim with a knife or pin will reveal a brass color underneath. Also, maybe someone can give you a precise weight of those exact strikes in Brass/Silver to compare with the weight of yours. Sorry I don't have them to give you the numbers but I'm sure someone on the board can help out. A solid silver should weigh more than a brass/silver combo. I have experimented with some $7 strikes and got a very satisfactory plating on them, the $10 would be a bit more difficult. The plating is pretty even on the ones you showed, to get that you might need a copper plate over the whole thing then a nickel plate then silver. I'm curious if it is silver plated or nickel plated. Are there any signs of oxidation?