I grew up shooting a 16 vh that was my grandfathers. Never considered any other gague until later in life. As Dean said, the 16 was fine on all manner of birds and waterfowl.

As in most matters under discussion here, Parker provided an answer.

From the 1910 Parker Small Bore Shot Gun pamphlet, here are data comparing the sub gauges 16, 20, and 28 to the standard 12.