Congrats!! Did he buy it new? If not, the previous owner may have, it's an easy rechamber, specially with the GBO Casull reamer. I wouldn't try it without a chamber cast being done, if there's no room for the brass to grow when it's exposed to upwards of 65kpsi, it could increase pressure even more which could be bad for the gun and the shooter. Chambered properly the CR45LC will handle Casull and 460S&W just fine.
Tim