We are not talking large quantities here. One bag could be inflated with the gas from maybe two shells and we may have detonated only a couple of bags a week with black powder and the rest with vendor supplied gas generators. Each test was recorded with high speed photography and data recorders and the analysis of the data obtained was time consuming. There were no laptops to crunch numbers with. There did not seem to be any difficulty obtaining the shells. They always had a supply. Since explosives were not allowed anywhere inside the Engineering complex so they built a small building on some vacant land they owned and did all the loading and storage in that building.
"Peace is that brief glorious moment in history when everybody stands around reloading" - Thomas Jefferson