US Bomb, Practice, Small, Type MB-4
The practice bomb, Type MB-4 is cylindrical in shape, with a nose plug and insert set into the forward end of the bomb body. A hollow fin section, with a spoiler band and four fins, is attached to the tail end of the bomb. The bomb contains a spotting charge.
The Type MB-4 practice bomb is composed of two major assemblies: the bomb body, and the fin section. The bomb body is made of solid metal except for space provided for the insert and the firing pin assembly. The fin section is hollow to accommodate the spotting charge and is secured to the bomb body by four equally spaced screws around the perimeter.