Short answers, pulled from the story.
James Sidney Stembridge founded Stembridge Gun Rentals after working as an extra on Cecil B. DeMille's The Squaw Man in 1913. The business officially began during World War I when Stembridge suggested setting up an arsenal for Paramount.
By 1940, Stembridge Gun Rentals had grown into one of the largest private arsenals in the country with 7,000 rifles, 1,200 revolvers, and 200 machine guns. The collection included Thompson M1921s and M1928s and was located at 5451 Marathon Street on a Paramount backlot.
On the 7th of December 1941, the day after the attack on Pearl Harbor, the US Coast Guard requisitioned the entire Stembridge Gun Rentals arsenal for use in the event of an invasion by the Japanese. Fritz Dickie, who had managed the company since 1927, was contacted to facilitate the handover of the weapons.
Stembridge Gun Rentals supplied the Thompsons used to kill Sonny Corleone in The Godfather in 1972 and provided 25 Thompsons for the 1990 movie Dick Tracy. The company also supplied a Thompson for Michael Jackson's music video Smooth Criminal and the actual rifle Charlie Chaplin had used in the 1918 movie Shoulder Arms for the 1992 biopic Chaplin.
Most of the remaining Stembridge Gun Rentals arsenal was auctioned in 2007, marking the end of an era that had spanned nearly a century. As of 2013, the company had moved to Glendale and was run by Syd Stembridge, while most of the arsenal ended up at Independent Studio Services.