Okay. This is very confusing but let's try to sort it out.
1. In your picture of the rear face of the cylinder, the S prefix is very obvious, as is the rest of the serial number. The S is, as always, located one charge hole over from the beginning of the serial number. So, the serial number on the cylinder is S123720. This part is clear.
2. The number you showed us on the side of the grip frame
is not a the serial number. That is an assembly number and it should match those that are stamped in the yoke area. That is why it does not match the serial number on the rear of the cylinder.
3. The correct grip frame location of the serial number is on the
bottom of the grip frame (butt of the gun). Look there and see if it is S123720, just like the one on the cylinder. If so, it may also appear on the inside of the extractor rod shroud, under the barrel.
4. Now this is where things get odd. That serial number would date the gun to about 1954 or very early 1955.
This is much too early for it to be a Model 27-2! Is it actually stamped MOD 27-2 in the yoke area? If so, the number on the butt isn't going to match the one on the cylinder, and we would have to conclude that someone has put a much older cylinder onto a Model 27-2.
I'm awaiting your reply with baited breath. Your post is an enigma to me.
