You said it has the "bug" screw. Do you mean the 4th screw or the 4th screw plus the smaller screw that holds the 4th screw in place? Some folks tend to misname the 4th screw as the bug; that's why I ask.

Have you tried a magnet on the cylinder? The earliest examples had aluminum cylinders (probably earlier than your sn, but it's worth checking).

The Standard Catalog of Smith & Wesson, 4th Ed., shows a range of $700 for Excellent through $1,300 for ANIB. You said the blueing has some chips, but for my money the box makes up for some of that.

My two bits.

__________________
Wrangler of stray Chiefs
Bob