That is likely just the result of a load tuning issue or a characteristic of the Baretta barrel (which I am not familiar with). 147gr 9mm loads can be highly accurate in part because the longer bullet is better stabilized by more contact area with the barrel. I had a G19 that would shoot sub 1 inch at 25 yards with Hornady xtp 147gr and AA #2 when the OAL was correct. OAL is critical for achieving correct pressures and good accuracy because the bullet must match up with the chamber's free-bore (space ahead of chamber where barrel has no riflings.). The Glock has a free-bore that is perfect for 147gr ammo. On the other hand I cannot shoot 147gr ammo in my beloved CZ P0-1 because it's free-bore is too short. Don't blame the bullet weight alone. It's just one variable in a system.