In fact, tests have shown that even #4 Buckshot lacks the necessary penetration to reach the vital organs. Only 0 Buck, 00 Buck, and 000 Buck penetrate enough to reach the vital organs.
Reading through the Boxoftruth paragraph, I disagree on #4 buck not being enough to reach vitals on a human at HD ranges. Of course disregarding an obstructed path(door, wall, chair) between the good guy and bad guy. With that said even then I think it's got spunk.