I "Tricked" My 4th Gen Model 27.! With Night Sights... 3 1/2 lb Trigger Spring Connector... 6 lb Trigger Spring... Adjustable Trigger Stop... Chrome Pins & Chrome Back Plate.! It's a 40cal... I have a 9mm Lone Wolf Barrel for Range Use & Sum Model 19 Mags.! It Shoots "Sweet".!