The proportion of US adults who own at least one firearm has been stable for the past two decades,1 with slightly more than one in five US adults reporting that they personally own at least one firearm. In 2015, for example, 22% of US adults personally owned a firearm (and one in three households contained firearms).2 However, because of population growth, the number of US gun owners continues to grow.2 It follows that more Americans have become new gun owners than former gun owners over this time period, raising questions about (1) how gun owner characteristics are changing and (2) what these changes may augur for future generations of Americans, especially with respect to exposure to household firearms among particularly vulnerable populations, such as children. In a recent issue of AJPH, we described how US adults who had recently become new gun owners differ from adults who owned guns for a longer period of time.3 We also quantified, for the first time, the dynamics of movement into gun ownership, estimating that approximately 10% of the 55 million US adults who currently own guns had acquired their first gun over the previous 5-year period.3 We returned to our 2015 National Firearms Survey, a Web-based nationally representative survey of 3949 US adults conducted in April 2015 (response rate 55%), to examine how demographic and behavioral characteristics differ between former versus new gun owners and, as well, to describe the reasons former gun owners offer for no longer owning firearms. Details of the 2015 National Firearms Survey are described elsewhere.2–4 To our knowledge, the findings we present are the only descriptive data from a nationally representative survey that speak to the dynamic nature of current or past firearm ownership