I believe that there is a possibility that it is a BB strike. It has left an anvil effect on the Obverse. Also a BB is 4.4 mm in diameter. These hits appear to be approximately 2 mm in diameter, which would mean that the depth should be around 1+ mm. It would be interesting to measure them as accurately as possible and do the calculation to check. The sides of the depression may slope upwardly at too steep an angle to be consistent with a BB strike, however - I just cannot tell.