Got into a discussion this AM after a couple rounds of skeet when one of my compadres saw the sorry condition of some of my 20 ga AA's. I understand there is no direct relation of pressure to recoil but it seems there must be some relation of pressure (lower somewhat when the mouth of a hull is cracked and degraded) to velocity. Maybe depending on the burn rate of the powder, the pressure where it counts (near the muzzle, I suppose) and ultimately the volocity of the shot, could be affected by the condition of the hulls.
