I’m sorry to hear of the deterioration of your pouches. How frustrating!
I think the problem is not with the leather, but that the acid in the vinegaroon (vinegar and iron mixture) used for coloring the leather ate it up. I’ve heard of this happening, and have been spooked (and advised) not to use vinegar on for that reason. I still use Fiebing’s leather dye.
Vinegaroon reacts with the tannin in vegetable tanned leather to change the color of the leather itself. The vinegaroon is a reagent, and not a dye.
Lots of people will tell you how to make vinegaroon, but very few mention neutralizing the acid after the coloration has been achieved. I tried it on a sample piece, and rinsed the sample pretty thoroughly with clear water after the coloration was achieved. The sample swatch seems to be intact, but it has only been a couple of years. Maybe some of the professionals here can advise us.
I would stick with vegetable (bark) tanned leather, in any event. Chrome tanned leathers can be corrosive to metallic objects over time. Chrome tanned leathers ought to work for a pouch, but I just wouldn’t leave anything stored in it. For a shot pouch, or “hunting bag,” I would use milled veg tan leather. It is more supple than the regular veg tanned tooling leather.
Best regards,
Notchy Bob