Rebuilding an original Hepburn over this winter and have a couple of questions on the numbers marked in various places on the rifle.

On the bottom flat of the barrel in the 'normal' position in front of the forend attachment screw, the serial #7618 is easy to see/read, as is the 32-40 cartridge marking. However, per the attached pic, near the threads  the barrel is also marked with 10523 & 32.40. Is the 10523# a build number?

Also, on the left side of the tang where the receiver is covered with wood, but as far forward as it could be located, the tang is marked 7212 in fainter, but 'straighter' (neater, better aligned?) numbers than the 7618 serial number, which is heavily stamped. Again, is the 7212 a build number of some sort?

The buttplate is also stamped inside with 7618.