Identifying 40% Ike Dollars

Lot of good information here.
I would like to add.
No 77 or 78,s had silver, unless in error.

1971 - 1974, all the 40% silver came from the mint it what is called
brown box (proof) or blue packs (UNC). The brown box coin were/are
in a single coin hard slab, the blue packs were/are in a single coin
mylar holder with a blue plastic (poker chip looking)token.
If you see the coins in these mint packages, then you know they are
40% silver.

The 40% 1776-1976 coins came in three coin sets, quarter, half and dollar.
Proofs came in a small book like display with each coin in its own
airtight type capsule. The BU coins came in a red envelope with
all three coins in the same mylar holder. If you see coins in
these holders, they will be 40% silver.

The S mint CU proof coins came in the regular proof sets (cent through dollar)
none of the regular proof set had silver coins (for the years above)

Of course if they are not in the original packages, then have to go back to
tissue test or weight.

It does when you use the [code][/code] tags.

1. Coin is Unc
     1. Coin is S mint it is silver
     2. Coin is 74-D or 77-D Do  tissue test
          1.  tissue test indicates Coppernickel - not silver
          2.  tissue test indicates silver, weigh the coin.
               1. Coin weighs 24.6 grams - Silver
               2. Coin weighs 22.7 grams - coppernickel
     3. Coin is coppernickel

2. Coin is Proof
     1. Coin is 71-S or 72-S - Silver
     2. Coin is 73-S, 74-S, or 76-S Type I do  tissue test
          1.  tissue test indicates Coppernickel - not silver
          2.  tissue test indicates silver, weigh the coin.* 
               1. Coin weighs 24.6 grams - Silver
               2. Coin weighs 22.7 grams - coppernickel
     3. Coin is coppernickel

* It is probably safe to assume it is silver. I've never heard of a silver plated coppernickel proof.