Fullered blade 502 mm long; MRD 23.4 mm

Apparently the same as the Type 2 Variation 2 bayonet except for a shorter blade.

Albert N. Hardin, The American Bayonet 1776/1964 

There are several basic forms of the long-bladed BG&M bayonets.  The most common variety has a slightly curved fullered blade.  This variation has a blade 19.75 inch (502 mm) long, 1.03125 inch (26.2 mm) wide and .3125 inch (7.9 mm) thick. 

The cast-brass hilt is 4.875 inches (124 mm) long.  It terminates in the unique flat bird's-head pommel which is associated to BG&M bayonets.  The upper guard flares out rather boldly to enclose the .922 inch  (23.4 mm) diameter bore.  Its external surface is oval and it terminates in a forward-pinched cockscomb finial.  The grip is circular in cross-section and is covered with concentric finger-ridges.  The pommel is flat on both sides and along the top.  The short stud spring is set vertically into the obverse flat.  The spring is attached by a screw at its lower end.  A short .375 inch stud groove is milled into the upper flat.  The only marking on these arms is a serial number of one or two digits, found on the lower guard flat or just forward of the stud groove.  The lock-to-muzzle distance is 4.3125 inches (110 mm).