Federal EFMJ, change in bullet shape

Hi guys,

I have two boxes of Federal Expanding Full Metal Jacket in 9x19 +p. Bullet weight in both cases 124 grs, code on the boxes are P9CSP1.
On the picture you can see that the left bullet has a hexagonal bullet head with a “F” and the right bullet has a circular bullet head with a “f”.
Does someone know the production period for the hexagonal and the circular bullet head?

Best regards

Chris