There could have been some incidences of Forced Conversion at local levels. I do not dispute that. Just like Forced "Nas-Bandee" of emergency time.
Some officials of Aurangzeb might have tried to build numbers...some armymen of Mughals might have killed many Hindus only for their faith. Such evil things unfortunately happen in this world.
But as matter of principle, you must restrict discussion to Islam, and not Muslim kings.
If Forced conversion is permitted in Islam, Prophet and his immediate Followers must have done it Most, as they had reached high level of power and control.
Why you fail to give examples from that part of history, if you have any.
That would be far far more convincing than actions of any criminal King
