I'm not sure about pressures, but I once read that handguns with short rifled barrels throw better patterns than longer rifled barrels. I had a 2 3/4" Charter Bulldog Pug .44spec that I always woods carried with two handloaded #12 shot cartridges and three hard casts. It was deadly with the shot out to 8-10yds. I was once in the woods with a buddy, blowing on how good I could shot a snubnosed revolver. He doubted it, so I say, throw up that can. I hit the can. WOW! He didn't realize that I was shooting shot, until I told him. Life is good.