I just picked up a S&W 65-5 4” round butt, the only thing that I wounded it that this one on the front and back strap has strait cuts from top to bottom and it looks to be factory. I can’t seem to find if this would increase the value of it.
Welcome! What you are describing are "serrated tangs" (aka grooved front and back straps), which were factory standard in about 1997-'98 and in guns with a B prefix (along with the other two letters and four digits of the SN). Usually only Target sighted guns had this feature. Probably doesn't affect the value much but is interesting to see. Hope this is helpful.