Question about a BH Parker

[Andrew Frank]

So I’m looking at a BH Parker and trying to decipher some things. As it sits, the stock is a total disaster, someone butchered it beyond repair by dovetailing in a comb. It has two sets of barrels, original Damascus 12 gauge barrels that are cut down to 26 inches, and a set of 16 gauge barrels that look like really late additions from Remington, the markings on the flats and side of the lumps look right but there is no marking on the rib at all. Both barrels are marked RK3 so they were returned in Nov. of 1941. Would it be safe to assume that’s when the barrels were added? The letter also say it was returned in 1919 to Parker Bro and along with other repairs a new extended rib. I’m wondering what that means?

Thanks for the help