WASHINGTON (Reuters) – The U.S. House Oversight Committee has asked the chief executives of three gunmakers to testify on July 20 as part of its investigation into the firearms industry following a wave of high-profile mass shootings, the panel said on Thursday. The panel called on the CEOs of Smith & Wesson Brands, Sturm, Ruger & Co, as well as privately held Daniel Defense to appear, according to letters sent to the companies released by the panel. “I am deeply troubled that gun manufacturers continue to profit from the sale of weapons of war, including AR-15-style assault rifles,” committee…