Choices in both of these departments are rather thin at the moment.
The UMP45 could work well as the security's counterpart to the insurgents' slow firing Uzi. Likewise, something like a PPSh would work well for the insurgent counterpart to the security's
bullet hose MP7.
I think something like an M27 for security and RPK-74 for insurgents would work well as lighter, more mobile alternatives to the slow, bulky M249 and PKM.