[2] Despite the fact that local folklore sets the establishment of their shop in 1807 the evidence suggests that Jacob worked for the Harpers Ferry Armory from 1808 until at least 1818, when he moved to Missouri and bought 160 acres (0.65 km2) of land in New Madrid.

[3] His brothers, John, Joseph and George Hawken also were listed as employed by Harper's Ferry up until the early months of 1818.

[1]: 7  Jacob also entered into a partnership with a St. Louis, Missouri gunsmith named James Lakenan which lasted until the latter's death on August 25, 1825.

After the death of his wife and father, he relocated to St. Louis, where he formed a fresh business, separate to that of Lakenan and his older brother.

[4] Their shop, though it excelled in gun-smithing, was also a bastion of old-fashioned craftsmanship; for up until 1848, they repaired and restocked tools as well as firearms and produced brass axes, tomahawks, gun worms and even basket-style hilts for swords.