I'm not a fan of the SERPA design, and think there are better alternatives available today. That being said, Rob does a nice job giving an overview of SERPA use (though he doesn't cover my #1 gripe-- mechanism failure that locks up the gun).
[video=youtube;-F0FBsXe6c0]https://www.youtube.com/watch?v=-F0FBsXe6c0[/video]
[video=youtube;-F0FBsXe6c0]https://www.youtube.com/watch?v=-F0FBsXe6c0[/video]