I wasn't putting it down. That scene settled it for me and Black Lagoon would always have a place in my favourites, but it's idiotic to expect it to be realistic. Black Lagoon is a anime done in the style of a western action film (and even makes a point of commonly referencing such films).
So it's got hot kick ass women, action packed scenes with a easy to follow plot and explosions. All the named characters can dodge bullets, all the punks can't shoot for shit and get killed with one shot and with the occasional one liner thrown in for good measure.
It was never meant to be taken seriously. Just sit back, relax your brain and let them entertain you with explosions, gunfights and hot chicks.