Are you measuring the chokes with a plug gauge or with a bore mic? The vast majority of 12ga/28" BSSs were choked M/F from the factory, so yours may be the odd factory choking or perhaps it has been opened. The silver trigger does indicate an early gun. I don't know about that "black chrome" because every one I have seen has been blued. The bluing will thin fairly quickly along the bottom of the frame from field carry. If yours is a PG gun with the fat beavertail, you can improve the looks and handling by reshaping and checkering the beavertail to match the Sporter f/e, and by stripping the gloss finish and applying an oil finish. These guns tend to be a bit heavy through the barrels so removing a bit of weight from the f/e can improve the balance and the looks.
The BSS is probably the best of the basic modern field doubles, strong and reliable, although a bit heavy. That weight makes it a great clays double and the 3" chambers make it a good duck gun. You can safely shoot steel through it if the chokes are not too tight and if you don't get crazy with shot size.
