Since the two models mentioned are built on completely different frames, in completely different calibers, and with different features, a picture is necessary to really sort this out.
Welcome to the Forum.
The M10 is a K-Frame with fixed sights.
The M27 is an N-Frame with an adjustable rear sight. It also has a checkered topstrap and barrel rib.
What is the serial number, from the bottom of the butt, including letters?
Jim