Bell's experiments showed that the pressure rise for a 1/4" long hull is between 0% and about 15%. Many folks are having good results with 2 3/4" reloads in shorter chambers. They use generally loads listed in loading literature of 5,000 psi to 7,500 psi, light shot charges and 1100-1200 fps velocity. The low pressure is kind to the metal and the low recoil is kind to the wood and shooter.
Most patterning results from light charge, low velocity, low pressure loads pattern at least as well typical loads - no magic.
Last edited by Rocketman; 06/12/09 11:59 PM.