The title makes it sound like Hamas is shooting Israel's bombs back at Israel, but Hamas' arsenal are primarily of Iranian origin. The article reports that they do scavenge explosives from unexploded ordinance, but not the amount. However, they do take large amounts of scrap like plumbing pipes from Israeli settlements, which are used to make bombs.
I'm not an explosives expert but I would hazard a guess that scavenging missiles and such that don't go off is not going to be a viable source of material to make more missiles, factoring in the risk involved.
The oft-repeated idea that Iran supplies the majority of Hamas weapons is also poorly sourced. It is usually attributed to the CIA's World Factbook or former US generals who now are talking heads for think tanks. These sources are highly biased.
But one thing that has been well documented is the Hamas unexploded ordinance team. They have over a decade of experience disarming and retrieving Israeli bombs from Gazan homes and businesses.
I see no sources, but I’m an internet armchair activist with no prior knowledge of the subject, nor any in the field, and the confidence and words in which you described your position have convinced me and won me over. You’ve won this internet argument and have my vote.
Every gun that is made, every warship launched, every rocket fired signifies, in the final sense, a theft from those who hunger and are not fed, those who are cold and are not clothed.
This world in arms is not spending money alone. It is spending the sweat of its laborers, the genius of its scientists, the hopes of its children..
-President Eisenhower in his ‘chance for peace’ speech