It is also a shaped screw at the end. It is rounded off and smooth against the main spring. This is easily done with a Dremel, file or emery paper after the proper length is determined. ALWAYS make sure the screw is fully tightened down and NOT left lose to lighten trigger pull! This is done by adjusting the screw's length.
Pre War MS screws are a different fit ..and sideplate screws bit smaller in size..I'd suggest picking few of pre war longer threaded MS strain screws if your into pre war Smiths sold off ebay. Usually sold as singles as pre war Mil & Pol or Victory Types or K22 MS strain screws.
Changed in the late40'ish -1950ish time period. Most
All external Smith Screws are what you see sold now.
Edit to Add..The Pre War Smiths used a slightly smaller size sized side plate set of screws.
This info has been provided courtesy of Handjector's and
Hondo44's extensive research on S & W history and factory changes over the Yrs....