Using the phrase "holding gun to head" can be intense and graphic. If you're looking for synonyms that convey a similar feeling without being quite so explicit, there are several options. One alternative is "pointing a weapon at oneself," which still makes it clear that there is a dangerous situation at hand. "Threatening self-harm with a firearm" is another possibility that adds a bit of detail about the nature of the danger. If you want to avoid guns altogether, you could use phrases like "putting oneself in harm's way" or "endangering oneself with a weapon." Regardless of which phrasing you choose, make sure it accurately reflects the severity of the situation.