CAMD RF 81-12038-54
"Due to a lack of homogenous armour plates 120 mm thick at the Gorohovets artillery proving grounds, it was decided to shoot at two plates: 45 mm and 100 mm angled at 30 degrees from normal. Both plates were mounted on a wooden frame and attached with metal bolts. 100 mm plate [illegible], the 45 mm plate was placed as close as possible. Due to deformations of the 100 mm plate from previous tests, the space between the centers of the plates was about 30 mm. The plates were square, 1.2 meters per side. Shots were fired directly. The gun elevation was set with a quadrant.
The first shot was fired at 200 meters. The shot missed, and it was decided to shoot from 100 meters. The second shot hit the wooden frame.
The third shot was fired from 75 meters. On impact with the armour plates, the ballistic cap was deformed, and the core shattered into small pieces. The jacket was deformed and got stuck between the 45 mm plate and the 100 mm plate."