Best For Deltoid Development: Dumbbell Overhead Press
Research performed by StrengthPro Inc. found that the dumbbell overhead press activated more middle-delt muscle fibers and fewer front-delt fibers than the barbell version. The middle delts make up most of the mass of the three heads, and provide width and roundness to the shoulders, so dumbbells should take precedence over a barbell when pressing for delt size.