BL-8 High Power 152 mm Gun

As we already determined, the 152 mm ML-20 howitzer was very effective against German tanks. However, after the Ferdinand's arrival on the battlefield, the Red Army started looking into guns with exceptionally high penetration. The most powerful gun they had at the time was the 152 mm BR-2 Model 1935. This gun was already tested in the experimental SU-14. A gun with identical ballistics, the BL-7 (OBM-43), was developed by the Special Design Bureau # 172. After refinements, the gun was indexed BL-8, and installed in the ISU-152 SPG, designated ISU-152-1. Let's take a closer look at the gun.

ISU-152-1

BL-8

This was quite a massive gun. The long barrel accelerated 43 kg 152 mm shells to about 900 meters per second. As for its destructive power, I will let these photographs speak for themselves. (Source: CAMD RF 38-11369-304). 

150 mm plate. Shots 1-4 were fired at a 30 degree angle. Shots 5 and 6 at 0 degrees.

180 mm plate. Shots 9-12 fired at 0 degrees. Photo #5 shows the front of the plate, photo #6 shows the rear. 

 203 mm plate. Shots 13-16 fired at 0 degrees. Photo #9 shows the front of the plate, photo #10 shows the rear.

As devastating as the BL-8 was, the design did not satisfy the RKKA. Work on a powerful gun continued, and the BL-8 was further improved to become the BL-10 (the BL-9 index was taken by a 122 mm gun). The BL-10 was mounted on the ISU-152-2, also called the ISU-152BM or ISU-152-10. By that time, the war was coming to an end, the Germanic gigantism proved to be containable with the D-25 gun, and work on a high power gun of a large caliber ceased.

ISU-152 with a BL-9 (OBM-50) on top and a BL-10 (OBM-53) gun on the bottom. 

CAMD RF 81-12038-268

A number of these guns were produced throughout the development process. You can currently find a BL-7 gun marked #4 in the Armed Forces Museum in Kazakhstan.