I use a .450 Rigby for backing up and hunting of dangerous game. In my opinion, the difference between it and the Ackley/ Lott, is that it can actually acieve the velocities at a safe pressure. When hunting in extreme tempratures, like the Zambezi Valley in October, pressure stays low. I have regularly used a load that propells a 500gr. Rhino bullet ( semi monolithic/ solid shank bullet simmelar to Trophy bonded Bearclaw) at 2400 ft/sec. in weather so hot that a Ackley loaded to 2300 jammed. On one occation, during a midday break from tracking buffalo, I extracted the bullet that I carried in the chamber, and it was too hot to close my hand on. I have fired simmelar hot loads, with no ill effects. I agree that its main advantage propably lies in the use of 600gr. bullets, and that is why I now load 600gr. bullets at 2300ft/sec.