Checking the 1905 San Francisco City Directory, I find --
Allen, E.T., Office 414 Market, R 2204 Jackson
In the commercial section under Arms & Ammunition I find
Baker & Hamilton
Bekeart, Phil. B. Co.
Claybrough, Golcher & Co.
Fischer & Bennett
Ladd, Edwin H.
Olympic Arms Co.
Reach, A.J. Co.
Shreve & Barber Co.
also the west coast offices of Marlin, Remington, Smith & Wesson, UMC and Winchester. I also checked under Gunsmiths, and Sporting Goods and no E.T. Allen listed.
In the 1900 San Francisco City Directory I found --
Allen, E.T. Co., E.T. Allen President, com. merchants, 416 Market
No mention in the Arms & Ammunition section.
Here is a link to on-line San Francisco City Directories --
http://sfpl.org/index.php?pg=2000540401
Knock yourself out!!