[Oatka]

The troy pound is about the same as a pound avoirdupois, which makes a troy ounce greater than an ounce avoirdupois.

I saw this bit of skullduggery on eBay, selling silver to the uninformed:
"4 standard ounces of 90% old U.S. silver coins (no junk) $120.00 Free shipping"

[captain_dave]

An old silver dollar has about 0.77 troy ounces of silver.