Smith Wesson 41 7 3/8" barrel mark?

[gwanghoops]

I have a 1965 Model 41 and was wondering what's with the vertical barrel mark on the left hand side near the front.

Looking at other 7 3/8" early 41s, they also had the same mark.

Really only shot this once or twice, so forgive me for my ignorance.

[flyer898]

There was a weight available for the S&W Model 41 when your pistol was made. The vertical mark is an index mark for locating the weight.

[gwanghoops]

Thanks! Makes sense. Exterior weights for greater weight and control than the internal OEM ones.