Illustrating the 'open' trigger guard function on a Navy model lipfire and navy model centerfire percussions.
<a href="//commons.wikimedia.org/wiki/User:Millermpls2" title="User:Millermpls2">Millermpls2</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>