Impaired proof.
There is no FB designation given to proofs. Given almost all are going to be FB due to the nature of the strike and the mintage. Compare 2million proofs to the 400 million business strikes. On a business strike there are more Inconsistencies in striking pressure, die wear, polishing, reusing dies, etc. These are all factors, especially in higher montages, that affect the strike and the amount of details on a coin. This holds true to all other designations as well, FBL, FS, FB...
Also, Business strikes graded below MS-60 are also not given a FB designation.
There is no FB designation given to proofs. Given almost all are going to be FB due to the nature of the strike and the mintage. Compare 2million proofs to the 400 million business strikes. On a business strike there are more Inconsistencies in striking pressure, die wear, polishing, reusing dies, etc. These are all factors, especially in higher montages, that affect the strike and the amount of details on a coin. This holds true to all other designations as well, FBL, FS, FB...
Also, Business strikes graded below MS-60 are also not given a FB designation.























