The Heritage of the Sioux by B. M. Bower

Classic western. The Flying U boys stage a fake bank robbery for film purposes which precedes a real one for lust of gold. According to Wikipedia: Bertha Muzzy Sinclair or Sinclair-Cowan, née Muzzy (November 15, 1871 – July 23, 1940), best known by her pseudonym B. M. Bower, was an American novelist who wrote fictional stories about the American Old West... She wrote 57 Western novels, several of which were turned into films.