The current explosive limit chart using in the oil and gas industry published with unclear condition of safety factor and consequence of overexposing temperature and time, resulting in many published papers disclose the possibility of expanding the safe-operating envelope of HMX. HMX is preferable because it typically provides deeper penetration than HNS but less stability at high temperature. Therefore, this study aims to maximize use of HMX for hollow gun perforation in typical environment in the GOT. The explosive temperature limit depends on two parameters, exposure time and temperature. The maximize use of HMX could achieve by, either ways, reducing the exposure time or extending the temperature limit line. Firstly, the operating time optimization is doable by using statistic record of the depth perforated by HNS and practical running speed together with a 20% safety margin. Secondly, expanding the temperature limit of HMX is a precise task because the HMX once exceeding the stability temperature, the perforating performance losses and explosion hazard arises due to thermal decomposition. However, this could be creditable by integrating the published explosive testing results over the current operating-envelope and applying a safety margin. The represented operating time, counting from running in hole to tool on surface, for perforation with E-line unit in the high-temperature environment could reduce by an hour. This operating time allows the temperature limit of HMX increasing by only 7 F, which considering as insignificant. The integrating result of three published paper indicated no explosive deflagration happens if the temperature is below the "Fiasco line" – introduced by a company, however, the operating time longer than 200 hours is not incorporated. By applying safety margin, the new operating envelope of HMX in the hollow carrier proposes between the typical and the Fiasco line. Combing time optimization and the new line, the HMX temperature limit extends from 375 F to 394 F for 2.2 operating hours. This new criterion has been applied successfully since 2018; 325 m of HMX achieved perforation condition without an indication of misfire or catastrophic self-detonation, resulting in reduce 50% of HNS consumption. In conclusion, the new temperature cutoff is valid for maximizing the use of HMX with a reasonable safety margin.