I sold Pete a Wm Gough engraved Aubrey that he put the pictures of on his website. Thos closeups of the disappearing middle bead (a patent by AJ Aubrey) were also my pics. They seem to show up around the net.
12ga, 32" F&F. Nice engraving and wood.
A heavy gun, I shot it quite aa bit before selling it.

Meriden/Aubrey usually stamped the Barrel material and the bbl length on the water table just above the guns serial number.
This is usually on the left side of the water table

They commonly used single letter codes for the steel types.
S-Steel,, T-Twist,, K-Krupp,,D-Damascus,,C-Chain Damascus
Then the barrel length in inches.

A common marking would be 'T30' for Twist barrels 30" length.

A '2' I'm not sure what the meaning would be.

If it's stamped on the opposite side of the water table (right side) from that where the ser# is stamped,,then it's the Grade of the shotgun.

Low Number= low grade,,higher the number higher the grade.
The grades ran into the 50 and I believe the 60 Grade numbers.

I've had more than a few Meriden/Aubrey shotguns and a couple of their pump and single shot .22's. Oddly no handguns that I can recall.
I still have one of their Model 1912(?) pump 12ga shotguns and a single shot 12 hammer gun. Just sold the hammerless single shot 12,,quite a nice gun in itself.
One of the nicest .22 pumps was a a Deluxe Model 1915 Meriden that I brought back from near death after a buffer got ahold of it at some point.