during my investigation of getting facts for buy myself a hunting license and a rifle (Poly tech m305, which is going to be in 4-6 years maybe), I tried asking the guys over Milarms surplus store near me, where to find some, but he recommended me some 5.11 gear, these one;
http://www.511tactical.com/All-Produ.../66-Pouch.html apparently according to him, these work quite fine.
so anything short of a med pouch, maybe bigger, is going to fit it