You can kind of learn a little bit about this pic from the rifle.

First, it can be fairly well dated from 1966-to-early-68 with the cleaning rod taped to the gun, as that was the heyday of functioning problems caused by the infamous powder switch and before the introduction of the chromed chamber.

Another pic of a cleaning rod strapped to a gun can be found on page 208 in THE BLACK RIFLE.
BR I and II are essential books if you are interested in the development and service use of the M16.