I'm not sure what "dull tops" means either.
The top strap, rear sight leaf spring and top of the barrel rib on the M-27 are checkered, but they shouldn't be "dull". The M-28 had the top strap bead blasted to a matte finish...surely you don't have a M-27 with the bead blasted top strap?
The backstrap isn't checkered, from the factory, on any S&W that I'm aware of. The backstrap, below the shoulder is vertically serrated