Jerry Noble's Notes on the Southern Long Rifle (Vol. 1) lists a L. Fitzpatrick, son of Reese Fitzpatrick who worked in Mississippi in 1885. See page 48. Additional details are in Vol 2, page 38 which further identifies him as Louis A. Fitzpatrick who worked from 1871 to some time after 1900.
There is also a Levi Fisher, who apprentice to George Hawken of Vicksburg, Mississippi around 1850. Levi was born in VA in 1801. See Vol 2, page 38. James Whisker's Gunsmiths & Allied Tradesmen of Virginia states that Levi lived from 1801-1865. His younger brother, George was with him. See page 33.
Whisker in Gunsmiths and Allied Tradesmen of Missouri lists on page 32 a Louis Froelich in St. Louis. He also lists the Prussian Lonzo Fredricks (1820-?) in Kansas City, Jackson, Missouri (page 31). Lawrence Fisher (1832-?) was active in 1850 in Warren County (page 30). Levi Joseph Fifield was a gun and blacksmith who joined the LDS. Born in 1803, he died in 1851 from blood poisoning (skinning an animal and cut himself). Levi joined the 500 strong Mormon Battalion (they didn't fight but marched out to CA where they were used as laborers).