But “Killing Floor benefits from a unique AK-47 model by showing incredibly detailed animations during slow-mo” is a “ORIGINAL CONTENT” not a standard one and as I’ve mentioned it before I would always do original content for myself.
We are talking about generic props. The line is very fine. In one game AK-47 is a generic (and doesn’t matter who made it as long as it looks good), in another game AK-47 is very original content, as you’ve said, with original anims and what not, and of course should be made in house. I always stated that.
Just like any tree for example. If your games in about group of commando running through forest, surely the trees may be generic. But if your game is about trees growing in forest, my opinion is that it is worth to make them “in house”, because that is a original content.