I did alot of research on this one. This Winter is being spent upgrading a good deal of my equipment. The bag I built is small at 7" by 7" and follows the lines of a 18th century bag. There is a whip on the reverse side to tie the bag to a sash or belt, the strap is narrow and adjustable by a button in the back attacgment. Also it has a game keeper attached to the strap.
The bag itself has a full divider and a folded gusset at the bottom.
All that is left to do is dubbin the bag after aging the sinew..
Dubbin is a application of a bag conditioner/waterproofing. There are alot of formulas out there. I use a beeswax, beef rendered lard, and cod liver oil mixture. I heat my bag in a oven and rub it in. Then heat the bag again to get the leather to fully absorb it.
The sinew is dyed with a alcohol/glycol mix and then the threaded area is sealed with a amber colored wax.