WASHINGTON — President Obama has taken on N.B.A. stars on the White House basketball court, golfed at the air base that houses Air Force One and even tried to polish his legendarily woeful bowling at the presidential lanes. But now it turns out that he has picked up a new hobby: skeet shooting at Camp David. At least that is the way he tells it. In an interview published last week, Mr. Obama said that he and his guests shot clay pigeons “all the time” at the retreat in the Maryland mountains, a revelation that surprised many and drew a...