He had only one opportunity at the world's heavyweight championship, but was defeated in a fifteen-round fight by Primo Carnera of Italy on October 22, 1933.

Later in life, Bimstein gave an account in interview, of a scene more reminiscent of the cinema: "I remember one day we were at a sidewalk cafe.

Believe me, I got back to the hotel in nothing flat..." Much more grim was his description of the Civil War in Spain beyond such high drama: "It was nothing to walk along the streets covered with hundreds of dead, and you couldn't tell when the fighting would break out anew."

Uzcudun, Bimstein, the other seconds and as many as "three hundred others" took refuge under the massive ring, until troops restored order—even with this, citizenry "continued rioting in the streets all night...." It was unfortunate for Uzcudun, whom Bimstein said "was the finest character among the fighters I ever met, square as they make 'em, game and tough, and in his prime a match for any of 'em.

During a sparring session with Franklin Rosalia (1911–1972), who also summered in Rocky Point, Uzcudun received a punch that knocked him down flat.

In 1936, Uzcudun fought on the Nationalist (pro-Franco) side during the Spanish Civil War reportedly from the first day of the conflict as a member of the Falange Española de las JONS.