In relation to the early 20th century drum makers of Boston, A. J. Oettinger was little more than a tangential figure. It does appear, however, that he was a very active participant in the musical instrument manufacturing and retail scene in Boston during the early 1900s, and a knowledgable one at that.
Oettinger's name is referenced more than a dozen times in Christine Merrick Ayars' Contributions to the Art of Music in America by the Music Industries of Boston, 1640-1936. While most of Oettenger's expertise appears to have been outside the realm of percussion instruments, he did brush shoulders with several well known drum makers of the time including Elias Howe, Thompson & Odell, and Blair & Baldwin. Amongst Ayars' footnotes we see that it was Oettinger providing information to the author about "Grandsire Baldwin" who after leaving Blair & Baldwin went to work for John C. Haynes & Company.
Ultimately, A. J. Oettinger was primarily known as a string instrument dealer, repairman, and provider of raw materials and parts to other makers. Earlier in her book, Ayars includes the following description of Oettinger's Musicians Supply Company which thrived for nearly 30 years until the owner's death in 1935.