It appears to a target trigger, also. Most have the narrow one. Mine has the target trigger as well. Yours is the only other one I've seen with that feature. BTW, of the five 45acp revolvers I own, the 1950 is my favorite shooter.
Right after I acquired mine, I looked at the SCSW both the 2nd Ed. Copyright 2001 and the 4th Ed. Copyright 2016. The price guide of the 2nd Ed. stated in Excellent Condition $675.00 and the 4th Edition stated $3,200.00.
The right stock on mine is stamped as shown in the picture in post #12 above. I think later on they were stamped in a single line toward the bottom of the right stock. I have not seen stocks marked the way your stocks are printed and not any marked on the left stock. Maybe others will know better.
I am far from an expert, but after reading page 40 of the "Standard Catalog of Smith & Wesson" 4th Ed. it seems to state written serial numbers on the right stock stopped around 1929. I have both an early wooden stock where it is hand written in pencil and an early hard rubber stock where it was scratched in.