Indentification help- RE:1880 PARKER BROS 12 Guage SxS

[Ryan Shirley]

Hello all...new here.

I am the new owner of a Parker Brothers 12 guage, manufactured in 1880. I am hoping that some of you may be able to help me out with the 'possible value', and understanding the markings on the gun. The seem a bit different than how they are described on parkerguns website.

Ok, here goes:
Serial # - 18228 (1880 manufacture year)

Grade - Can't find this on my gun...says it 'should be above the serial on the waterboard, but mine doesn't have anything above the serial on the washboard. There is however, a 'F' on the underneath side of the barrel (see pic of flats)

Markings on underside of the barrel ('flats')
TT in parentheses "(TT)" - No idea what this stands for
48- this is the weight of the barrel. I assume 4lbs 8oz
A letter 'F' - possible referring to the Grade?
'02' on the barrel lug
The number 9508 - no idea what it means

Top of barrel
Says 'Plain Twist'

Ok, other than that, I am not sure if the stock has been replaced/refinished...if you believe it has, let me know. If you can tell me 'how you know' that would be helpful too!

Thanks. Any information you can give me regarding exactly what I have would be very helpful. See pics.