The Real Reason for the 1934 National Firearms Act?

According to Wikipedia, "[t]he impetus for the National Firearms Act of 1934 was the gangland crime of the Prohibition era, such as the St. Valentine’s Day Massacre of 1929, and the attempted assassination of President Franklin D. Roosevelt in 1933." However, Prohibition ended on December 5, 1933, and Giuseppe Zangara's February 15, 1933, attack on Franklin Roosevelt and Chicago mayor Anton Cermak was with a .32 caliber revolver, purchase or ownership of which was not affected by the NFA (although pistols and revolvers apparently were one of the central features of the Act as it was originally proposed). The Washington Post similarly contends that Prohibition era violence was the impetus for passage of the NFA. NPR similarly contends that the NFA was the result of Prohibition era gang violence, and adds:

Food riot

         When Roosevelt became president in 1933, his fellow Democrats controlled both the House and Senate by substantial margins, and there was already momentum to do something to rein in guns. 

        For instance, Sen. Royal Copeland, a Democrat from New York, was promoting a federal ban on the sale of fully automatic guns. 

         "We can never be free from the menace of promiscuous killings until the possession of firearms is everywhere restricted to persons of known character," Copeland said. "To this end I shall press my bill for passage through the United States Senate." 

         There was talk in Washington of an outright ban on fully automatic weapons. But Roosevelt was wary of that — not because of the Second Amendment, but because of the Interstate Commerce Clause. The Supreme Court had already imposed strict limits on the ability of Congress to regulate commerce. 

         Instead, Roosevelt backed a tax and registration scheme known as the National Firearms Act, which the president signed into law in 1934. 

         It applied to short-barrel shotguns and rifles, and to fully automatic weapons like machine guns.

 Keep and Bear Arms has an online copy of the hearings, and, doing a quick search, I was unable to find any references to Zangara or an assassination attempt on President Roosevelt.

       Subsequent pushes for gun control legislation, especially over the last 50 years, have generally been motivated from some national tragedy, such as an assassination or shooting spree. So it is interesting to me that there is not a single reference to the assassination attempt on President Roosevelt. Thus, I wonder, given the country being deep in the Great Depression, if there was not another motive for enacting a law that, at that time, would have only allowed wealthy people to own machine guns and what not.

       I recently started reading Locusts on the Horizon and it relates the story of the 1931 Food Riot in England, Arkansas. Although I won't reproduce the books account, here is a shorter version from the Encyclopedia of Arkansas:

        The England Food Riot of 1931 occurred after the drought of 1930 caused major crop failure across the region, leaving many farmers unable to feed their families. The Depression was occurring across America, and the majority of people in England (Lonoke County) and the surrounding area were destitute and desperate. As a result, approximately fifty angry farmers converged on the town of England, demanding food to feed to the starving members of their community. The crowd grew to include hundreds once in town, and the merchants, with assurances of repayment by the Red Cross, agreed to open their doors and offer all they had to avert any violence from the mob. The crowd dispersed peacefully, but the incident created a nationwide stir. 

         England is positioned in central Arkansas between Pine Bluff (Jefferson County) and Little Rock (Pulaski County) in what is considered one of the richest agricultural regions in the world. It was established in 1888 after the railroad was built through the area. The town grew quickly and prospered well in the early 1900s. 

        The drought that came in the summer of 1930 devastated the region. Farms normally abundant in cotton, corn, rice, and hay were laid to ruin by the lack of rain and high temperatures day after day. It was not until December of that year that any relief arrived, which was in the form of the Red Cross. Assistance from the Red Cross was meager at best, amounting to approximately one dollar per month for each person in need. 

         On January 3, 1931, H. C. Coney, a tenant farmer from Lonoke County, was visited by a neighbor who was distressed because she was unable to feed her children. He decided that he must do something, so he loaded his truck with several other neighbors and headed to England to demand food from the Red Cross. Though the original group of men consisted of approximately fifty farmers, some armed, reports state that anywhere from 300 to 500 came together once in the city proper. The Red Cross, which lacked the forms necessary for people to apply for aid, took the brunt of their anger for the promised food never given to those in need. The merchants, either out of fear of what the mob was capable of or out of the kindness of their hearts, offered food to the people that day. 

         According to some eyewitness accounts, there was no violence, and the term “riot” might not be the best description, as any possibility of an actual riot was averted due to the generosity of the storeowners. There is little doubt, however, that the scene could have become ugly had the farmers not been mollified. 

        One witness to the event worked part time for the Associated Press and promptly called his editors with the story of the riot. Newspapers from New York to California picked up the story. Until then, Arkansas governor Harvey Parnell, along with the Red Cross, had tried to downplay the severity of the situation, saying that they had everything under control and that no one was in desperate need. But now the plight of the people of England was known nationwide.

          Keep in mind that this was not an isolated incident. For instance, the beginning of food riots and hunger protests is considered to be the February 1931 Minneapolis food riot, which required 100 police to quell. Food riots subsequently broke out in San Francisco, Oklahoma City, St. Paul, Van Dyke, and many other cities. The Ford Hunger March, sometimes called the Ford Massacre, was a demonstration of unemployed workers that took place on March 7, 1932, in Dearborn, Mich, which resulted in four marchers being shot to death by police and Ford Motor Company security; a fifth marcher later succumbed to gun shot wounds he had received. On top of this, there was significant labor unrest across the nation, farmers protested low farm prices and foreclosures, and there had been riots to halt evictions in New York. And, last, but certainly not least, in 1932, 10,000 out-of-work military veterans and dependants marched on Washington, D.C., to demand payment of military service bonuses that had been authorized by Congress in 1924. On July 28, 1932, the Army attacked the veterans' encampment and drove them off.

         We should consider whether the NFA was not due to prohibition crime, which was winding down, but the increasing civil unrest during the Great Depression; and that its primary purpose was to disarm the populace of its most effective weapons in the event of revolution.