I was wanting to compare those two cartridges to get an idea of how trim a 450 NE 3-1/4" barrel could be. For an identical chamber pressure, and with the same steel type, the outside diameters of the barrel over the chambers should be proportional to the cartridge diameter. That is to say, a cartridge with a case only 90% as fat as another could have a barrel only 90% the diameter and still handle the pressure. From what you say, however, the 450NE has higher chamber pressures, so you could NOT make the barrels proportionally trimmer and still handle the pressures. My previous reading had suggested that this round has historically had the option of trimmer barrels. It would seem this is at the risk of a lower safety margin.