I revise any previous opinions I had on personal sidearm choice. Given enemies without gasmasks, an MGL-6 with laes gas (and/or splash) grenades. Given opponents with gas masks and/or sealed armor, I need a teammate. Said teammate to carry a supersquirt with acid filled paintballs to break the seal. Sure, the grenades are 185-200ny a shot but they also drop anyone who can't make 10 hits on their toxin resistance.
Edit: Make that leal gas. If you need more than 90 minutes, you're doing something wrong.