"served as an Orderly Sgt. under General Jackson" is a broad statement, like saying "he served under Forrest". Records of the service of Mississippi Territory Volunteers and Militia in the War of 1812 is very sketchy in detail of their service, especially at the Battle of New Orleans where we know there were Mississippi Territory men, like Hind's Cavalry, but infantry men are much harder to pin-point, mainly due to all the attention to the Jackson's Tennesseans. The MDAH has service records of individuals from that period, it helps if you have a unit to help the search.

The picture is very interesting. It is a reversed image. Mississippi seems to have the most photographs that show those tall shell jacket collars. I only have one example of a Mississippi soldier wearing a 10 button jacket, James D. Malone of Co. G of the 17th Miss, but he had piping on the sleeve not colored cuffs. Can't tell the color of the cuffs and collar, they could be red, green or blue. The weapon, going by the trigger guard and strap ring it looks like an older style musket, mayby flint or flint conversion. I would swear he was some sort of cadet by the cut of the uniform as a whole, his gig line is perfect, very unusual for a recruit volunteer or untrained militia. No shoulder tabs, no horizontal piping, short jacket instead of dove tails or frock, looks to be 1862 or after. Thanks for sharing, great picture!
David