Don’t put your finger on the trigger of a plugged-in tool which is loading and in use.
Glue gun specifications
Glue guns come in low-temperature and high-temperature (hot-melt) versions. Low-temperature glue guns operate at approximately 120 °C (248 °F) and are well suited when high temperatures are undesirable, such as gluing lace and cloth. High-temperature guns operate at approximately 190–210 °C (374–410 °F) and produce a stronger bond. Dual Temperature guns have a switch for both low- and high-temperature use.