(1) The pouch is not British, the hardware (buckle and lift the dot fastener) is U.S. in style and if the color is OD as you said in post #7, it is an American bag but for what purpose I have no idea.
(2) The worn, medium brown sling is Swedishfor the M96 Mauser.
(3) The light color sling may be for a South American Mauser.