The barrel markings are as described, a mis-read of a weak rolled stamp of "BARRELS" but the crown/GL mark is indeed on the underside of one barrel.
The barrels are 30" but its suggested that they may have been cut off from an original 32 but the barrels appear pretty close in the 2nd photo so I don't know. The damage to the rib could be from a hack job.
I thought it interesting that the word TRAP is on the butt plate, which is probably original but badly worn. (Can't make out the word trap due to bad focus)
I had a pretty good restoration gunsmith give me a price of about $200 to restore the rib so I decided to pass on the gun but it was a fun search.