Thanks this is exactly what I was looking for. I will get busy on ordering the letter. Thanks again!!I did some bracketing using known ship dates of pre-27s and your .357 Magnum shipped between July and December 1953. S&W deleted the upper sideplate screw in 1956 and ordered model numbering in 1957, although actual model numbers on guns didn't show up until 1958. I recommend purchasing an historian's letter of authenticity from the S&W Historical Foundation. They are $100 and will return that to you if you decide to sell the gun.