The M31 was made from 1931 until 1949 and is considered one of the best and smoothest pumps ever made. It was made in many Grades and configurations.
Both the M31 and Winchester's M12 were made when hand fitted all solid steel and walnut quality counted with American gunmakers and sportsmen. I own both guns and will not venture an opinion here on which gun is better.
Today's gun buyer has a toilet paper attitude about his gun. He buys the cheapest he can find and when it stops working he throws it away. The M12 & M31 came from a different era, sadly.