List of British Ordnance Terms - C.R.H.

C.R.H.

Calibre Radius Head. The radius of a circle with the curve of the shell's nose on its circumference, expressed in terms of the shell's calibre. The longer and more pointed (and hence streamlined) the shell's nose, the higher the C.R.H. Typical c.r.h. for British shells leading up to World War I was 2: e.g. the curve of the nose of a 2 c.r.h. 6-inch shell was equivalent to the curve of a circle with a radius of 12 inches. Shells of 4 c.r.h. were soon developed in World War I, identified by A following the shell mark number, B for 6 c.r.h. and so on. For modern streamlined shells post-World War I, 2 numbers were necessary to more correctly denote a shell's c.r.h. characteristics. For instance, the World War I 6 inch 26 cwt howitzer shell was 2 c.r.h., the World War II Mk 2D shell was correctly described as "5/10 c.r.h.".