A Japanese Type 14 made by the Nagoya Torimatsu Arsenal in February 1944 (19.2).  In very late 1943 the heavily milled or grooved cocking knob was abandoned by Torimatsu in favor of a solid cocking knob with a knurled or checkered gripping surface.  The Nagoya Kokobunji factory continued the use of the grooved knobs.  The original checkering on the solid knob was rather fine and apparently not well liked so, very quickly, the design was changed in favor of a coarser checkered surface.  The fine knurled examples can be found from 18.12 (December 1943) until 19.2.  Virtually all 19.1 examples made by Torimatsu have the fine knob.  Some exist with a 19.2 date and a very few can be found with an 18.12 date.

Immediately below is a comparison picture showing, left to right, grooved, fine & coarse knobs.