I tried finding another post, but could not find what I am looking for. I just got a 642 with the 2.5" barrel and pinned front sight and am wanting to change it out for either a night sight or, I prefer, a Hi-Viz type sight. Also, is this a fairly easy thing to do? What I mean by easy is, will I be able to replace the roll pin with another or will I have to drill a new hole/modify the barrel? Any help would be appreciated, thanks.