The 215 was originally sold under the Riverside Arms name. According to Researcher01 on the Shotgun World web site,
"Generally Stevens changed from using the Riverside name for their lower priced line of guns to using the Springfield name about 1930. A Springfield Arms Co. hammer gun the No. 215 is still in the 1931 J. Stevens Arms Co. Wholesale Price Sheet, but is gone by the 1933. So, that pretty much narrows your gun down to 1930-32."
"The Feb. 10, 1914, Patent date refers to Patent No. 1,086,378 issued to G.S. Lewis and assigned to the J. Stevens Arms & Tool Co. of Chicopee Falls, Massachuetts. The gun first appears in the J. Stevens Arms & Tool Co. General Catalog No. 54 as the Riverside Arms Co. No. 215. After WW-I the company became the J. Stevens Arms Co., a wholly owned subsidiary of Savage Arms Corp. of Utica, NY. The gun is still a Riverside Arms Co. No. 215 thru Catalogue No. 57, which was dated 1927. By the January 2, 1930, J. Stevens Arms Co. Wholesale Price Sheet the gun is a Springfield Arms Co. No. 215."