In 1763 Spain took over Louisiana from the French, and held it till 1801. This was all lands that drained by the Mississippi on the west and north of the red river.
Although some Spanish moved in to the area trade was still a French concern.
The Spanish kept guns out of the hands of peasants
Guns would be mostly French smoothbores in this area, and the French trade guns have been found
Tribes actively traded also acting as middlemen and moved English guns in to this area.
france got back this land in 1801. Napoleon wanted an American empire. But needed money and sold it in 1803.
American Indian trade was handled by the government. And they hoped rifles would be more popular with Indians than fusils. They made specific trade rifles that were plain versions of Pennsylvania style guns. Brass mounted rifles of about .50
Between 1803 and 1821 private Americans did trespass, and coming misty out of the south had southern style rifles, but Pennsylvania, Ohiio and Connecticut made guns would be showing up.
After 1821 private companies took over the trade. So any American rifle could get moved in to this area. Again tribes like the Osage and Caddo acted very much as middleman moving American guns in to East Texas
French men in this area still had plenty of smoothbores.
After 21 there were the legal immigrants in to Texas, but the New Mexico government never got a handle on stopping illegal immigration, and the new Texan settlers had no intrest in steming the tide.
In 1846 Texas captured a band of border ruffians who were Mexican, American and French and they had a hodgepodge of guns, including brown bess, French and American muskets and various rifles