A self opening gun is one that uses spring power to push the action open when the lever is pushed . There are several basic types that either use the power of the mainspring or those that use the power of an additional spring. Do not be confused with the likes of the Cogswell and Boss guns often falsely described as "assisted openers " as the ejectors have spring pressure on them which pushes against the face of the action when the gun has not been fired .
Your gun is just lose .