56x45mm rounds. These rifles are constructed on our patent pending “Multi-Caliber” selector switch know-how that enables people to simply change amongst calibers without any equipment or modification by just depressing a small lever about the remaining aspect of your receiver to remove a pin and rotating out the selector change. https://noveske-rifles-for-sale79305.blogscribble.com/18180497/what-does-noveske-rifles-for-sale-mean