As I posted below, less eloquently, that is where my antenna twitch the most. There are a lot of discrepancies and oddities there and it's definitely the point in the story where things don't hold together so far.

If he was going to ditch the gun he could have just left it there as they were certain to search the roof-tops, so why break it down (delaying escape), run, escape, then reassemble and dump it?

I'll be interested to see what we are told later.