Not so much about guns per say, but anyone who has some time should read this piece about how the rebels are supplied from abroad and how convoluted that supply chain has become:
http://www.lrb.co.uk/v35/n04/ghaith-...e-easy-lessons
Basically, it is a giant mess where rebel "battalions" of 10-20 men are constantly formed, merged or dissolved, any semblance of organization is in name only and where the best funded and equipped units are the jihadist groups.