I've been using the setscrew fsb's forever, it's perfect for setting your windage zero exactly without messing around with the barrel slot or pin. I can always get a perfect zero centered windage adjustment using these sight bases. When set correctly, I then loctite the allen screws one at a time so as not to disrupt zero, then use loctite "green" wicking compound to seep into the barrel bands. This procedure will hold as well as the pain in the #%$ pins will. I know, because when trying to remove the fsb at a later date, it is just about impossible without using a torch and a deadblow hammer.