The problem with the clip that was missing at the crime scene, as well as the misidentification of the rifle as a Mauser for three days, is discussed in this paper which was linked earlier in this topic:
assassinationresearch.com/v1n2/gtds.html
The paper's conclusion is the investigators made a fatal mistake when they put a clip into the Carcano prior to walking out of the TSBD with it. A mistake that proves a conspiracy.