To dream of nail gun or power nailer represents the ability to effortlessly keep a situation staying put. It may also reflect the ability to easily keep multiple people or problems permanently under control.
Negatively, a nail gun may represent a heavy handed approach to preventing a person or situation from getting out of control. Going overboard or the risk of going overboard preventing change.
Example: A man dreamed of firing a nail gun. In waking life he sent a very scathing email to two relatives who were disrespecting him behind his back to get them to stop. The reflected the ease with which he set his family straight.
Example 2: A man dreamed of seeing another man shot at him with . In waking life the dreamer was involved in litigation demanding a settlement while the person that injured him was quickly trying to control the legal conflict with delays and obstacles to prevent progress with litigation.