There is a book on " Recreating the 18th century Hunting Pouch", by Tim Albert- a member here- that is available from Track of the Wolf that should answer part of the question. And, there is also a book written by Madison Grant on "The Kentucky Rifle Hunting Pouch", also from Track. I don't think you are going to find orthodoxy in fasteners vs. no fasteners when it comes to these personal items. That is, there is no hard and fast rule.
Hunters who walked to and from the areas where they hunted had less need to fasten the flaps, than hunters who rode horses and mules to get there, perhaps. But if you have ever RUN a Seneca Course with a pouch that didn't have a fastener, you learned very early to shorten the shoulder strap, and use an elbow to keep the pouch closed while you were running! :nono: :shocked2: :blah: :hatsoff: