Actually, on his way to shoot the president Czologosz wrapped his pistol (a .32 Ivor Johnson "Saftey Hammerless") in a handkerchief, which he then placed in his coat pocket. When he approached President McKinley, who was shaking hands with people in the crowd, Czolgosz pushed aside the president's out stretched hand, pulled the revolver from his pocket and fired two shots into McKinley. He would have fired more shots but the revolver was knocked from his hand as he was thrown to the floor by a man (sorry, the name escapes me) standing to the side of the president.
It is generally thought that Czologosz's first shot was the one that proved fatal as the bullet passed through McKinley's stomach, spleen, and kidney before lodging in his back. The second shot (possibly fired as Czologosz was being knocked to the ground) was a grazing shot, and ended up in the president's shoulder, where doctors were able to remove it there at the Pan-American Exhibition. The bullet from the first shot couldn't be located, and doctors elected to leave it in place, a fatal decision. The wound became infected, gangrene set in, and a little more than a week after he was shot, McKinley died.
It is generally thought that Czologosz's first shot was the one that proved fatal as the bullet passed through McKinley's stomach, spleen, and kidney before lodging in his back. The second shot (possibly fired as Czologosz was being knocked to the ground) was a grazing shot, and ended up in the president's shoulder, where doctors were able to remove it there at the Pan-American Exhibition. The bullet from the first shot couldn't be located, and doctors elected to leave it in place, a fatal decision. The wound became infected, gangrene set in, and a little more than a week after he was shot, McKinley died.