I personally think that barely anyone do "Hacks or Duplication" for Xbox. Sorry bro. But there could be.
Also, I don't think it is possible for anyone to give you JUST diamond guns. You will get the rank as well if you are wanting and talking about duplicating. If you want your rank to stay and you want all diamond guns, the person duplicating it for you has to get to your rank and then duplicate it for you which I think the person can't be stuffed doing. The person would just give you the dup instead of putting so much effort into what you want.