Shooting a few rounds...
The term ``round'' derives from the earliest ``point and shoot'', manufactured by Kodak in the 1800's. It came loaded with 100 rounds, and was sent back to Kodak for processing, after the end of the roll was reached. Their slogan was ``you push the button, we do the rest''.
And, of course, the images were round, because of the vignetting (limited field of view) of the lens.