I have a .38 nickle Trooper myself. It will be interesting to see if anyone here claims to know if the .357 cylinders were heat treated different. I carried a .357 on the job many years. I suppose the standard answer will be "no" for safety sake but it`s hard for me to believe a 357 and a 38 made at the same time were heat treated different. Hell, they made a .38 special python too! For the few made it`s hard for me to believe they heat treated those different! I suppose they got orders from some police and guard departments insisting their guns be .38 special, not 357. Thinking on reaming the cylinder to .357?