You can tell a moly coated bullet by its color, especially a jacketed bullet. They will have a grayish-bronzeish color to them. A cast lead bullet will also have this color but won't be as obvious. The advantage/ disadvantage to coating bullets is a BIG topic for discussion. Some say coating will allow higher velocities at lower pressures some say its hogwash. Some say it allows for easier cleaning some say hogwash. Some say it causes barrels to wear out prematurely, again, some say hogwash. Honestly I'm still on the fence as to if there are any advantages or disadvantages