There is a world somewhere between reality and fiction. Although ignored by many, it is very real and so are those living in it. This forum is about the natural world. Here, wild animals will be heard and respected. The forum offers a glimpse into an unknown world as well as a room with a view on the present and the future. Anyone able to speak on behalf of those living in the emerald forest and the deep blue sea is invited to join.
On amurs in captivity being larger, remember we have no real pure bred Bengal lengths in captivity. And any that we do have aren't differentiated from area to area. They are just labeled "Bengal" which of course can be a large variation between places in India and neighboring areas. So who knows how large a Bengal from Nepal would be in captivity.
Next thought is this: I assume Assam is the same as the Serengeti.
Lions in the Serengeti are said to be fairly average at most but lions in the crater are said to be the largest. But the crater is practically in the same area as the Serengeti.
So Assam tigers may be normal compared to kaziranga tigers which are said to be the largest.
Once more proving that specific factors will determine unusual results.