The pair of performance center 627's I have in 2 5/8" and 5" ...are both " Round Butt" N frames...and to my knowledge there are no square butt model 627's .....I would have preferred Square Butt frames - especially on the 5".
S&W's Web site is hard to navigate....and I couldn't find any note in specs that they are round butt..../ when I went thru picking those 2 guns out last year it was difficult....I ended up calling them before I placed the order with my local shop....