I'm guessing they were running multiple armor hardeners at the same time.

My ideal balance to the most powerful tanks in the game should be countered with the most powerful av weapons and skills in the game. Meaning a group of 3 ppl (since the tank is 3 ppl), all with 5 in swarms, 5 in specialized swarms, along with 5 in light sharpshooting and 5 in specialized sharpshooting. All using proto swarms and dmg modifiers. However, if your grp of 3 ppl doesn't have this, then you can make it up with adding more ppl to a full squad. Then there is wether its a sheild tank or armor tank because it matters wether your swarms or forge.

I have as of yet to run into a tank where I thought that even with a full squad, just using standard weapons, would not pop a tank, but boy i'd love it if I was wrong because in time, they will be everywhere and I can complain about giving me back my dumbfire, greater range for forges, gripe about the first swarm skill being virtually pointless, and lots of things.

I consider the first swarm skill to be pointless because it deals with blast radius, something that was left over from many many builds ago. The current blast radius is 1m, at skill 5 it should be 1.25m. Thats so small, you wont even notice, and the splash dmg you get from that is 15dmg per missile. The only time you may ever see anything from this skill is when you kill a lav and the driver jumps out just before it. Although, I say it's the lav expoding that kills the running driver and not the splash dmg, but others say otherwise. This skill doesn't directly effect how well you use your swarms. The only thing it does is allow you to use a better swarm launcher. Only the proficiency skill will increase how well you use a swarm launcher. However, its only a 15% dmg increase, so if you don't like the role, then you've already done enough skilling into it to be useful to other av ppl when a tank comes around.