I have been trying for several years to find out the grade of my great great grandfathers lefever shotgun. It is is very good condition, no rust, little to no pitting in the barrel, Damascus barrel, all matching serial numbers, overall great condition. The serial number is C36726F. It has a bunch of fancy engraving with a woodcock on one side and a duck on the other. I believe the "f" in the serial number is the grade, but the "f" grades I looked at, do not look like this firearm. It appears to be 12 gauge, but isn't marked anywhere. It has a patent date of 1872. The stock is in great condition also with a few scratches. I will try and add pictures tomorrow, the mobile version will not allow me to add pictures.