Based on the machine sewing I would date this poiuch to post 1880. While viable sewing machines had been around since 1849, dedicated leather machines were first introduced in 1878 or thereabouts. There were still lots of muzzleloaders being sold as late as the 1890's (in some areas even later) to those wanting a less expensive firearm than the repeaters. The type and color of the discoloration on the pouch may mean it was hemlock tanned, which presented some unique problems for dying.
As for conservatorship of the pouch - IMO do some research online or seek professional help via a museum, etc., because based on the amount and type of damage oiling or conditioning can increase the damage. Bark/veg tanned leather can get what is called red rot due to pollution, and once it sets in there is no turning back so a hermetically sealed case may be the best way to save.
It seems to be of a nice well thought out design.