7.62 x 51 Nato

from left to right :
RA 50, FA, FA, FA
Aluminium cases
blackish green Alu case, RA 50
light green Alu case, RA 50
light brown Alu case, FA,
light grey, Alu case, FA

Which ine is the scarcest ?
Thanks
JP

The RA is the most common. The FAs are all about the same rarity and value.

Thank you very much
JP