Funny you mention this story. I was just thinking the other day that I need to be a little more careful wrapping the leash around my fingers or else I could get my finger broken. Not so far fetched at all it seems...
My suggestion for dealing with a leash-reactive puppy is to pay close attention to anything that he might react to and distract him BEFORE he starts pulling/reacting. This takes constant vigilance to be in time before he reacts and high value treats/toys to get him to focus on you despite the distracting prey.
Also, please don't ever play laser tag with your dog. You didn't say that you did but I learned a little late in the game that laser tag can cause severe OCD behavior and make his prey drive even stronger.
Linus van Pelt Haus Juris. My Sweet Babboo, born March 17, 2014.
Madeline Ronan Heart (Maddie) Dec 1997 -- November 22, 2013 Rescue GSD, Sable