More of a "General Layout" drawing than a "blueprint", but NICE find, all the same.
I have one a lot like it, but of the Mk 1 Owen SMG. Nice to look at, but you would be hard-pressed to derive any valid dimensions from it.
Keep an eye out for the "full-colour" instructional posters for the AK variants; the Russians put out some very nice "den decorations" over the years. See also the
Swedish
ones for the 84mm Carl Gustav AT gun and, the classic, full-coloured
Finnish
lithographed posters for their early Luger pistols; VERY hard to find and often starting to crumble if not correctly stored.