RE: .16 GA. Question?????
You can certainly still buy 16 guage ammunition for it. You won' t find nearly the variety of loads and don' t shoot steel or other hard shot through the full choke barrel. It' s not recommended, since it could damage the barrel.
But lead shot can still be used in full chokes, if the the shotgun is in good operating condition. A good gunsmith can check that part out for you.
I have Browning " sweet 16" auto with a full and a mod. barrel I picked up about 30 years ago used when I was in the service for very little. I loved to shoot it. It was the most accurate shotgun with slugs I' ve used for deer hunting.
Can' t tell you about this particular shotgun though.
MinnFinn