How many boxes you need to get gold weapon?

It 1000 boxes per weapon and you can get it from 1 or from 1000 it totally random

http://sl.uploads.im/t/6JqMb.png

As you can see I try 5 boxes only

http://sl.uploads.im/t/rF52o.png

and get gold version

http://sk.uploads.im/t/zBb8o.png

Mission score for full Crown

http://sm.uploads.im/t/PUvyo.png