I'm thinking of killing myself with a shotgun blast to the brain (details not clear yet), should I be concerned with any potential suffering involved, assuming I do things "correctly"?

A friend suggests that the moment of death is phenomenologically "frozen" - the experience of dying is "tenseless" and "feels eternal". Is this of any particular concern given what is generally understood about the brain and consciousness?

If shooting myself causes suffering, should I be concerned that the moment of death will feel like eternal suffering? Any help appreciated, thanks.