So far it looks like all the gun upgrades are unlocked by completing challenges and all the guns are unlocked through story missions. Is this the only way or can I get them through Guerilla mode the way R6 Vegas lets you unlock guns through ranks in Terrorist Hunt?
"We, Jaina, are the New Jedi Order... and this is OUR war." -Kyp Durron
far as i've seen geurilla mode you only get weapons dropped in crates and you just pick from whats available there. Then the campaign weapons are unlocked by doing campaign, and adversarial stuff is unlocked by doing adversarial.