The Spire IV features all new Proactive Feeding logic. Unlike previous Spire models, which required constant sensor readings from every shot occasionally adding in unnecessary spins while shooting, and potentially resulting in slow rates of fire from a sensor malfunction; the Spire IV features the new Proactive Logic. The Spire IV starts feeding the instant the first shot is fired, and continues to feed automatically, without relying on continuous sensor readings until the stack is full. This is the same proven technology incorporated into the CTRL loader, which works more consistently and reliably on every type of marker.