I don't think hunting animals with an assault rifle is a thing....unless you just want to kill animals which imo is not hunting. Imagine shooting a rabbit with a weapon shooting 200rounds/minute, assuming you hit it there won't be anything left to recover from it.
on your question now, I believe the devs have already been asked at some earlier point about modern day weapons and from what I recall the answer was they didn't intend to. They intended to add only bows, crossbows, then I think a flintlock was mentioned at some point as well as cannons (not for hunting). So basically more primitive weapons.