Yeah, Carl did the right thing. A little harsh but it's the Zombie Apocalypse so you do what you have to do! The kid should have dropped the shotgun, end of story.
The 50 BMG jammed and we all know Hummers have run flats but they did show them blowing out when it went over the spikes sooo we have to go with the premise that it had 4 flats.
I watched it again and it's definitely the sound of a casing hitting the floor after Andrea shot herself with the Python. They need to step it up on the firearms stuff. I did notice the Gov.'s slide locking back as he head shot the people he had just gunned down. I think it's the only time I've seem a slide actually functioning.
"An unarmed man can only flee from evil, but evil is not overcome by fleeing from it"