“Sub-caliber devices were used in the training of artillery soldiers and allowed them to train without using more expensive full-size ammunition and reduced gun barrel wear.
Pictured is a 75mm M1897 gun fitted with a T2E2 sub-caliber mount holding a Springfield M1903 rifle. The rifle would fire a bullet downward on the same trajectory as a full-size cartridge, allowing soldiers to practice firing the gun and targeting.
It is likely that almost everything pictured was produced at Rock Island Arsenal, including the carriage, recoil mechanism, rifle and mount.
Sub-caliber devices. (nd). facebook.com/RIAMuseum. photograph. Retrieved May 26, 2022, from https://www.facebook.com/RIAMuseum.