Other than weighing them, is there any easy way to guess whether an 1864 Indian is bronze or Copper-Nickel? I have a filler that I'd like to place in the right slot. Its sort of rusty looking, reddish in color, but not as brown (?) as the bronze ones get. do either metals rust? TIA
Not really, weighing is about the only way. Neither of them really rust, but any coin can get rust stains on them from being in contact with a metal that does rust.
Sure, just look at them. The copper nickel alloy and the bronze alloy have almost the same density but the copper nickel coin weighs almost 50% more. So the copper nickel cents appear to be almost twice as thick as the bronze ones. If you look at the edge of a CN cent the first thing that will strike you is how thick it is. (A copper nickel cent would be close to the thickness of a Sac dollar.)
Flying Eagle cents are also Copper Nickel alloy and are about the same weight and thickness of their Indian Head counterparts.
