Interesting

[CINDERS]

Yes your on the money its to do with the bullet weight at 160 Gn but also at the top of the drawing you can read what ever the acronym S A C Minute (Could stand for Small Arms Committee ?) 4409 VII underscore then under that we have 8-12-09.

So as stated it appears that this drawing is for the trailed 160 Gnr as hayboy suggested in due course proceeded with the 174 grainer I'm not sure the No. 4409 is the number of listed changes that have been made at that point 8-12-1909 in time with regards to the small arms in service.
So I learnt something today not only from the drawing which I think I snaffled off the web years ago and never paid any attention to the weight nor the date of the drawing also the fact that the site here contains very knowledgeable personnel who are onto it.
I did a PL thing dangled half a carrot to see what turned up, I mean this in a good way, thanks guys hope this was just a little bit of fun for you.