The Turkish big guns weren’t all that effective. Their rait of fire was abysmal, once ever three hours or so, and their accuracy was worse. To be more effective than pure luck they had to get close enough to the city walls to be in range of the city’s many smaller more accurate guns. They were like the Turkish pipers and drummers- aiming to intimidate the defenders with their noise and with the sheer size of the cannons which were actually technologically obsolete before they were first cast.
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