Hello. In a nutshell: BU means Brilliant Uncirculated, it is a grade. Uncirculated means it (the coins) has no wear 1921 Morgan is a morgan dollar made in 1921, 90% silver, 10% copper (somone will have to confirm this, I forget if that is exact.) stainless
BU literally means Brilliant Uncirculated (The coin has no wear). So BU can technically be any coin that is Uncirculated (MS60-MS70), but it usually refers to lower grade uncirculated coins (MS60-MS63). That's it.:thumb:
