These bullets are sized AFTER they are powder coated, so they are the same size as the regular cast bullets. Being that the coating is more slippery than normal lead, ammo loaded with this coated bullet produces LESS pressure than regular lubed cast bullets. People have been able to use higher powder charges and are seeing much higher velocities with less pressure signs than with the regular cast bullets. So, there really is nothing to worry about. You should develop your loads starting at least 10% under maximum and work your way up with these coated bullets just like you do with every other bullet. Prudent loading procedures still apply, these aren't magic and should be treated like every other load development.