NO INFORMATION IS AVAILABLE about A. V. Milyer. “Mordecai’s Pipe” appears to be the only story written by anyone with this name, and it is not impossible that this name is a one-time pseudonym of another pulp writer—an extremely common practice during the height of the pulp era, in the 1920s and 1930s.
The story has been interpreted to suggest that somehow the eponymous pipe came to life. A more likely explanation for the events that come to pass is that an outside agent, certainly a ghost, was responsible. But you may decide for yourself.
“Mordecai’s Pipe” was originally published in the June 1936 issue of Weird Tales.