Most likley an assembly number.
45 Smith and Wesson
smith and wesson.
No engineering changes.
Enhanced
A shotgun made for Smith and Wesson, sold under the Smith and Wesson name.
Standard Catalog of Smith and Wesson
The Wesson part of Smith and Wesson.
Horace Smith, Daniel Wesson
Smith and Wesson will tell you if you call them
Smith & Wesson was founded in 1852.
In this forum's context, Smith and Wesson, Target Sights.
No engineering changes have been made.