That didn’t take long. Sen. Chuck Grassley (R., Iowa) and Rep. Darrell Issa (R., Calif.) said they were expanding their probe into a troubled anti-gun-trafficking program, two days after the Justice Department announced a shake-up of officials who oversaw the program. Rep. Darrell Issa (R., Calif.) (AP Photo by Harry Hamburg) In a letter Thursday to Ann Scheel, the acting U.S. Attorney in Phoenix, Messrs. Grassley and Issa essentially put the Arizona district office on notice, saying its role “in the genesis and implementation of this case is striking.” They sought extensive documents – emails, memos, notes and the like...