Missing the obvious point again? Re-read this: cooldown between shots is now basically half of what it was before, magazine size was increased from 5 to 7. Do you even understand sheer magnitude of these buffs?
Are you missing the title of this thread? Its about Ostwind vs. Vehicles. The buffs were very strong against infantry, but against tanks a 23% chance of penetrating the weakest medium in the game is not "strong". If you think it is, I dont know what to tell you. That means it fails to pen 3/4 shots regularly, shots which only do 40 damage to begin with....