Ball bat with optimized barrel wall spacing and improved end cap

A ball bat extending along a longitudinal axis and configured for hitting a baseball or softball, the bat comprising:

• a handle portion having a distal end region;
• a barrel portion coupled to the handle portion, and formed at least in part of a fiber composite material, the barrel portion including a proximal end region, a distal end region, a central region between the proximal and distal end regions, and at least an inner wall and an outer wall, the inner and outer walls defining a first separation and being configured to allow for independent movement between the inner wall and the outer wall upon impact with the ball, the distal end region of the barrel portion having a substantially constant outer diameter, the outer wall configured for directly impacting the baseball or softball;
• a tubular sleeve positioned within the barrel portion such that the barrel portion fully overlaps the tubular sleeve, and including a proximal end region and a distal end region, the proximal end region of the tubular sleeve coupled to the distal end region of the handle portion, at least a portion of the tubular sleeve separated from the inner wall to define a second separation, the second separation being within the nominal range of 0.030 to 0.125 inch when measured radially from the longitudinal axis, upon impact with the ball the barrel portion deflects inwardly at the impact location such that the inner wall operably engages the tubular sleeve, the first separation being within the nominal range of 0.0005 to 0.005 inch when measured radially from the longitudinal axis;
• and
• an end cap coupled to the distal end region of the sleeve and to the distal end region of the barrel portion.