Abstract-In preparation for the high luminosity upgrade of the Large Hadron Collider, the LHC Accelerator Research Program (LARP) in collaboration with CERN is pursuing the development of MQXF: a 150 mm aperture high-field Nb 3 Sn quadrupole magnet. The development phase starts with the fabrication and test of several short models (1.2 m magnetic length) and will continue with the development of several long prototypes. All of them are mechanically supported using a shell-based support structure, which has been extensively demonstrated on several R&D models within LARP. The first short model MQXFS-AT has been assembled at LBNL with coils fabricated by LARP and CERN. In this paper, we summarize the assembly process and show how it relies strongly on experience acquired during the LARP 120 mm aperture HQ magnet series. We present comparison between strain gauges data and finite element model analysis. Finally we present the implication of the MQXFS-AT experience on the design of the long prototype support structure. Index Terms-High Luminosity LHC (HL-LHC), Interaction Regions, quadrupole, LARP, Nb 3 Sn magnet, shell-based support structure, short model.