Scorpion/Viper with backpack?

[Andy746]

Well viper and scorpion can't use backpacks, but during a fireteam i saw a viper use 2 primary weapons. A g36e and a grenade launcher? Does the specialist backpack work for viper?

 

[Jordan B]

Viper is a specialist. Specialists can use 1 primary weapon, and a special item in their "special" slot.

The M32 Grenade launcher can only be placed in the special slot, and therefore counts as a special item, just like the rest of the specialist items.