Berry's Hollow Base allows the bullet to be longer and provides more contact area with the barrel and rifling which will stabilize the bullet and improve accuracy. The bullet profile is longer but the weight of the bullet remains the same and you can load these bullets using any published load data for a jacketed bullet as long as it is the same weight bullet. The Thick Plate allows these bullets to handle velocities up to 1500 feet per second and is ideal for competitive shooters who are looking for increased accuracy and higher velocities needed for 9mm Major loads, .38 Super Comp/Open guns and the .357 Sig. For the 9mm they recommend a COL of 1.060" For the .38 Super they recommend a COL of 1.250" For the .357 Sig they recommend a COL of 1.135"