This period includes Trans Mississippi expansion, the war for Texas independence, the Seminole wars, and the Mexican war.  The uniform is basically the same throughout the period.  Sky blue coats are worn by enlisted infantrymen and artillerymen, dark blue by all other personnel.  In the beginning of the period, the 1825 style forage cap was in use and saw some continued use into the late 1830’s even though the leather forage cap was introduced in 1833.  Both issues were replaced by the M1839 forage cap “Wheel hat” which saw service to the beginning of the Civil War.  Trousers were broad fall front, giving way to the fly front type in the 1850’s. 

Within this period the standard firearm of the army changed from flint ignition to the percussion system.  This was accompanied by a drastic change in cartridge boxes, from the earlier types made on a European pattern to the 1839 rifle box and 1839 musket box which were made on a uniquely American pattern.  Remember the Mexican war was fought mostly with flint muskets and the 1808 or 1828 cartridge box.