Here's an electronic verion of the Richmond Daily Dispatch that includes an article on the "Mobile Rifles" and their part in the seizure of Mount Vernon Arsenal.
http://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:2006.05.0191

It appears this company belonged to the "Alabama Volunteer Corps" in 1860.

Also known as the "Mobile Rifle Company", the "Mobile Rifles" organized at Mobile, Alabama, Feb. 22, 1836 (also given as Dec. 10, 1846), and mustered in state service on March 20, 1861. Members enlisted in Confederate service and left Mobile, Ala., Apr. 24, 1861.