I have been very lucky in my collecting endeavors and have been fascinated with the "position" of rifleman; the below shows the rifleman's pouch, note that the sling was a white buff and branched off to accommodate the flask. The thought process was that the rifleman companies could go farther afield from supply and could best manage with lead balls and loose powder.
The rifleman's pouch is one of the most rare leather accouterment pieces in the collecting field, in fact Dorsey's wonderful treatise on "American Military Belts and Related Equipments" mentions this fact. They were only issued briefly, had a lifespan of 6-7 years and went through a major war (Mexican). Estimates are that 74,000 may have been produced and issued with the M1841 rifle and the rarest piece is the actual rifleman's flask, which was replaced by the "Batty and Ames Peace flasks". The picture shows the "Peace Flask".
The second piece is a rifleman's belt along with a M1841 rifleman's box, these were used with the Mississippi and M1855 rifle. The belt is patterned off the French rifleman's belt. Note the shield flap cap box, on the obverse would be extra wide belt loops to accommodate the wider rifleman's belt.