The serial # is 590?.
The rifle weighs about 12 lbs. The barrels seem very heavy at the breach, thicker it looks than most I have seen pictures of. At the muzzles they seem average from pictures I have been looking at.
I have an older James Braddell cape gun in .577 Snider and the muzzles on the Jeffery are much heavier. In fact, the whole action, barrels and everything are far beefier.