Capillary ultra-high performance liquid chromatography (UHPLC) is currently a method of choice for the sample separation step in LC-MS-based proteomics. However, capillary columns are much less robust in comparison to their higher flow countertypes. Because of easy contamination and blocking, they often need replacement. That makes them a markedly expensive part of the total LC-MS analysis cost. In-house packing of UHPLC capillary columns saves a lot of money and allows customization. However, the standard packing procedure in the 100-bar pressure bomb works well only for HPLC columns but is too slow for UHPLC sorbents. Here we provide a description of an optimized FlashPack protocol applied to the same 100-bar pressure bomb setup. The method is based on packing from ultra-high sorbent concentration slurry and is developed for in-house manufacturing of UHPLC capillary columns of unlimited length in reasonable time.