99E 22 HP 20" lightweight barrel, serial #2692xx
99G, 303, 20" lightweight barrel, serial #2780xx, last version of the lightweight barrel sight
99G, 300 24" medium weight barrel, serial #2909xx. First version of the medium weight barrel sight.
99K 250-3000 24" medium weight barrel, 2986xx, slightly different than 2909xx
99K 300, 24" medium weight barrel, serial # 3094xx, a really early example of the integral base that uses the dovetailed front sight. This type of base was used until about 1955.