We did back it down to remove the brittleness, but this has to be done correctly..and don't ask me how, to preserve the aux-treatment results. All I know is that it went back into the furnace for a period of time at a lower temp. End result is that the metals structure/crystal lattice is realigned in more consistent manner throughout the material and other non carbon impurities are precipitated out which increases the "toughness" (real engineering term) of the metal. No carbon is added, as this would increase the brittleness, and we wanted some elasticity in the metal. This particular frame is a hammer gun, and is pretty dang thick to begin with. I proved it with 500NE 30% over load and it mic'ed out at factory original specs. I backed the regulation load down to 75% for a 55% safety margin. This is on a 3.25" case, so it is even lower pressure. My philosophy is doubles should have big bullets, big cases and low pressures. IMHO.