Terrorists recycling unexploded Israeli munitions?

According to an article in the Islamic Jihad-oriented Palestine Today, the percentage of unexploded IDF ordnance in Gaza is considered a "gift from the sky:"

Abu Maaz of the resistance in the zz el-Deen al-Qassam Martyrs Brigades of the military wing of Hamas made clear that dozens of missiles and rockets by Israeli aircraft over the Gaza Strip in the recent war did not explode, and Hamas was quick to dismantle them and use the material that is inside.

He said: "After the war of aggression was stopped, we discovered dozens of rocket-propelled grenades which did not explode ... a gift from the sky. We in the resistance, we found the treasure trove".

"Abu Anas", an expert in explosives engineering al-Qassam Brigades, confirmed that the resistance is in the process of dismantling the missiles that did not explode, and making use of inside and outside.

Abu Anas noted that 5% of the rockets shot by Israel did not explode...

They go on to say that since there is a scarcity of raw materials in Gaza to manufacture missiles, these will come in very handy.

They also quote a YNet article about this phenomenon, which I could not find in English.