After the Soviet takeover of Georgia in 1921, he went in exile to the United States where he would naturalize in 1926. Having briefly worked for a minor aviation factory in Rhode Island, Grigorashvili, by then known as Gregor, was recruited as an aircraft designer by the Dayton-Wright Company in 1921, Curtiss-Wright in 1923, Seversky Aircraft Company in 1932 and Chase Aircraft in the 1940s where he worked until 1953. In 1934, Gregor founded his own firm Gregor Aircraft which constructed an original light plane 1GR-1.