FWIW---I got my webbing by doing a search for webbing on the web. Ended up buying hemp. Came fron some outfit in California. After a lot of research and a visit to Valley Forge to look at originals I determined that plain/basket weave was as close as I was going to get to period webbing for the colonial cartridge boxes i was making at the time. What you find in a lot of cotton webbing, and hemp also, is a twill/chevron which I have never seen on a period box or shooting pouch. Also difficult to find cotton webbing any wider than 1 inch whereas some of the hemp I have is 1 1/2 and I believe it is available up to 2in.
Steve