Casull can become unreliable and unpleasant to shoot. upper-pressure levels, heavy bullets tend to jump crimp - tying up the cylinder. (wouldn't this be great in an emergency) Also, fired brass can stick in the chambers." [/I]
I knew I had seen that warning somewhere....
I'm pretty sure I remember reading about an interview with someone at S&W saying basically the same thing - the gun can handle 65,000 PSI but you start running into issues like hard to eject brass. This causes people to complain or they want to send the gun back to be "fixed" even though there is nothing wrong with the gun.