The 155 mm shell is one of the most often-requested and supplied items, which also include air defense systems, long-range missiles and tanks. Already, the U.S. military has given Ukraine more than 1.5 million rounds of 155 mm ammunition, according to Army figures. The obstacles the U.S. faces in ramping up production can be seen at the Scranton plant. The Army has new contracts with plants in Texas and Canada to make 155 mm shells, said Douglas Bush, an assistant Army secretary and its chief weapons buyer. The Scranton plant is ill-suited for that task: an accident with an explosive could be devastating.