Ball bat with optimized barrel wall spacing and improved end cap

A ball bat extending about an axis, and configured for hitting a ball. The bat including a barrel portion coupled to a handle portion, a tubular sleeve positioned within the barrel portion, and an end cap. The barrel portion is formed of a fiber composite material, and includes a proximal end region, a distal end region, and an inner and outer layer. The layers are separated by a first separation configured to allow for independent movement between the layers upon impact with the ball. The sleeve is coupled to the handle portion. A portion of the sleeve is separated from the inner layer by a second separation within the range of 0.030 to 0.125 inch when measured radially from the axis. Upon impact, the barrel portion deflects inwardly such that the inner wall operably engages the sleeve. The cap is coupled to the sleeve and to the barrel portion.