With his local prominence in Quincy, Browning was elected the justice of the peace. He came to know a young lawyer by the name of Abraham Lincoln who was an overnight guest in his home on at least two occasions.
In October 1838, Governor Lilburn Boggs issued the Extermination Order that caused the Mormon followers of Joseph Smith to flee Missouri. In his capacity as a judge, Browning came into contact with many of the Mormon exiles. Curious about the new settlement of Mormons in the swampy lands of Nauvoo, Illinois, Browning paid a visit to Nauvoo. His meeting with Mormon Prophet Joseph Smith caused Browning to convert to the Mormon faith. His conversion led to him being ostracized by the community in Quincy. Browning sold his gun shop and land in Quincy.
He moved to Nauvoo, Illinois and joined the Mormon community in 1840, where he established a gun shop. Guns that Browning produced during these times were labeled "Holiness to the Lord - Our Preservation." The Browning Gun Shop has been restored as a museum, and is open to the public at no charge.
Browning fled Illinois with Brigham Young in late 1846 to escape religious persecution. He settled in the temporary Mormon community of Council Bluffs, Iowa (then called Kanesville in honor of Thomas L. Kane) and repaired guns for the Mormon settlers who were migrating to Utah. He was awaiting Brigham Young to invite him to join the main body of settlers in Utah. When the Mormon Battalion was formed during the War with Mexico, Browning wanted to join them, but was told by Young that his skills would not be needed by the soldiers as much as they would by the main body of pioneers in Kanesville.
As was common in the Mormon community at that time, Jonathan Browning was a polygamist, having taken three wives. He fathered 22 children; prominent among them was the gun designer, John Moses Browning, one of the most important figures in the development of modern automatic and semi-automatic firearms.
Browning received the word to join the main party of Mormon settlers in 1852. He left his gunshop in Iowa and migrated across the Rocky Mountains as the captain of a group of pioneers. He arrived with six wagons and six hundred dollars in the Salt Lake Valley. Browning moved to Ogden, Utah and established a gun shop there. His activities were limited to repairs in the Ogden shop, however. His son John Moses recalled, "We ridiculed some of the guns we fixed, and I damned some of them when Pappy wasn't near, but it never occurred to us to make better ones. He was too old, and I was too young."
- John Browning & Curt Gentry. John M. Browning, American Gunmaker. New York: Doubleday, 1964.