All examples that I have seen have a "posterior" screw, and are not pinned; and although I have not personally disassembled a Baltimore gun, I'm almost sure Larry is correct in that this screw secures an overhanging sear in a very similar fashion as the "posterior" pin on the Syracuse Arms gun that Frank Hollenbeck also designed. From my personal observations, any Baltimore gun above Grade B is a hard to find item. I have a Grade C "project" I'll finish someday; a 12-bore. The gun is missing the butt plate, but the stock is un-cut with excellent figure, checkering, and the unique ebony grip cap. The gun frame still has lots of original case color, sharp engraving, and screw slots are untouched and perfect. This gun obviously saw very little use; but some knucklehead cut its beautiful Damascus barrels to 18". I've obtained a great set of 32" fluid steel barrels thru the generosity of Daryl Halquist, as well an excellent set of 28" Twist barrels. The 32" barrels will fit the frame almost perfectly, and the gun will function if I use an extra A Grade forend I have; but until this barrel set is properly fitted, the original C Grade forend is not compatible with the 32" barrels in place. This will be a beautiful gun when properly restored. And based on my limited knowledge of the Baltimore gun, barrel steel names were not marked on barrels tubes themselves (at least on Grades A, B, and C); but one can determine the barrel steel type used (Twist, Damascus, or fluid steel) by inspecting barrel flats. If the barrel tubes are Twist, one will find a "T" stamp thereon, with Damascus barrels a "D" stamp; and fluid steel barrel flats will feature an "S" ID stamp.
