There are two Tandy Leather stores in Michigan, one in Grand Rapids and the other in Detroit. Most Tandy stores I've been in have VERY helpful people and it is a good place to ask questions.
Generally speaking, most folks like a pouch made from around 3 to 3 1/2 oz. Veg (Vegetable) Tanned Cowhide leather, though some of us like it as high as 4 oz.
Leather thickness is rated off so many ounces weight in a foot square of leather. Here is a chart explaining approximate leather thickness and pieces of leather.
https://s-media-cache-ak0.pinimg.com/736x/2a/60/90/2a609049b3f505dff2e0282ca9122c24.jpg
Veg tanned leather comes in "natural" color that many folks like to dye using a period "vinegaroon" mixture or modern dyes.
There are also Oil Tanned leathers that come already dyed and you pick the color you like because you can't dye it after the oils/wax is factory worked into the leather. These leathers are actually a little thinner for the oz. weight listed than what you would expect comparing to Veg Tanned leather. For example, Tandy's Stoned Oil Sides are rated as 4 to 4 1/2 oz, but in thickness are actually more like 3 1/2 to 4 oz. leather.
https://www.tandyleather.com/en/product/stoned-oil-sides
One thing to warn you about is you do not want a hide that has been "milled" or impressed with some kind of grain pattern on the smooth side. (This is done on some leathers for garment or upholstery applications.) That just would not be correct for a period pouch unless you were an extremely wealthy person in the period and if you were, you would probably not be traipsing around the frontier with a rifle gun. So stick with leather that is smooth on the smooth side.
Tandy can also provide you with tools you will need as you begin. Just please, Please,
PLEASE DON'T waste your money on that stitching tool with a wheel of thread in the handle. What you need is a good awl and two needles and linen thread to sew leather, not that monstrosity stitching tool that many of us bought before we knew better. :redface: :haha:
More info coming later.
Gus