Browning makes a screw-in hi-viz site that will fit any vent rib gun, including Beretta. You can also try the Browning "Bird Buster" magnetic light-pipe site. I got mine for $18.95.
Benelli Cordoba (20 ga. & 12 ga.)
Browning 725 Sporting (12 ga.), Maxus Hunter (MAX-4 & Hunter)
2 Golden Retriever "Hunting Buddies" & a crazy lab pup