A small diameter crossbow bolt includes a small diameter shaft having a leading end with an insert to receive a point. The trailing end of shaft has a nock and adjacent fletching. The insert receives a point, such as a target point, broad head, or other point known in the industry. A circumferential spacer is positioned along the shaft between the insert and nock and moved along the shaft as needed to locate the insert for a particular weight distribution, center of gravity positioning, or to separate the spacer from nock. The insert, nock, and spacer each have a diameter substantially equal to the diameter of a prior art bolt. When the diameters of the nock and spacer are equal to the diameter of a prior art bolt, the small diameter crossbow bolt of the present invention can be used interchangeably with prior art bolts without modification to the crossbow.