I don't think this is an issue of it being impossible, it's an issue of it being absurdly unreasonable. Perhaps a highly cohesive squad of veteran players can pull it off, but when you have a 5 to 10 enemies with a sentry camping the bunker there's little to nothing a group of randoms can do. Cohesive squads are by far the rare exception, not the norm. By and large it's hard enough to convince people to do a mediocre job at reviving or dropping ammo, let alone storm a bunker with any rhyme or reason. No one wants to throw themselves at the problem and die repeatedly so most just quit and go do something else. In my experience it never ends with a successful clearing, but rather everyone gives up and eventually the people inside get bored and leave. It's poorly designed, and what's worse, it's just not fun. I genuinely don't enjoy this map, so I think I'll just forgo it until someone decides it needs improvement.