Considering that both the solids and softs I use are Woodleighs, you'd think they would basically be the same, and at a glance they appear to be. No doubt there's some sort of difference, I just don't know what it is. I'd guess it's the slightly more blunt design of the solids, which gives the bullet a tad more edge and pressure, allowing the use of less powder than its more aerodynamic soft cousin. Sound about right?