When Assman advises it removed "digenerate tris"
This is what it's talking about
They must be edited in maya to resolve this
How? "digenerate tris" :-\
There many ways, most popular is to make all moving parts their own mesh and combine rest to one mesh that is binded to j_gun (note that sights, etc. are considered moving parts for hidetags, but you can ignore them if you aren't using sights.).