As anyone who has an mp c.o.r.e. knows, the rear sights are different. Finding a non co-witness sight set was tough enough as is, and to make it more difficult my stock sights were hitting about a inch high at 10 yards. I called Dawson and they recommended trying thier "stock" sights first, and wouldn't you know that they hit dead center. So basically Dawson's sights were better for the mp9 p.c. core than the Smith and wesson stock sights.