An adjustment system for a fastener pulling head includes a swivel adapter, an adjustment member, and a retention member. The fastener pulling head includes a frame, a jaw, and a drawbolt body, the adjustment system. The swivel adapter is configured to engage with a proximal end portion of the drawbolt body. The swivel adapter defines an internal bore. The adjustment member is disposed within the internal bore and configured to engage the drawbolt body. The retention member is configured to engage and secure the swivel adapter at a location within the drawbolt body. When the retention member is disengaged from the swivel adapter, the pulling head can be rotated to cause the frame to move relative to the drawbolt body to adjust a gripping force of the jaw.