The <B> under the barrel means that something specific was done to
the barrel. Like maybe it was replaced, and serial-numbered to the
frame. The serial number on the rear face of the cylinder should be
a very fine, small, and lightly-stamped serial number. An original
serial number under the barrel would also use the same small, fine,
number stamps, and they would be very close to the frame. Does it
look this way ? If possible, get us some close-up pictures of the
serial number in all three places; butt, rear face of cylinder, and flat
under the barrel.

As to some decoration on the rear grip stap, get us a picture or
two , of that. Without seeing a picture, I don't know what that might
be.

Mike Priwer