What is the criteria for weapon XP? Is it just kills or do headshots, offensive, defensive, avenge, revenge, etc count as well? Do challenges for the weapon count towards the weapon's rank progress? What about general weapon challenges; ie "get 25 headshots w/ SMGs" or proficiency challenges?
The reason I ask is because I use a lot of different weapons (I have 11 different primaries on my 10 classes & I use all my classes) so it takes me awhile to get them ranked up to the high 20s & I just got my 1st gun to level 30 and it says I need 89,800 XP to get to level 31 -- that seems like quite a lot.