These and Remington Model 31's were some of the smoothest pumps ever made. They just have a feeling of quality about them missing in the more economical to produce pumps that replaced them.
I have my Dad's 20 ga. modified chock. It was made in 1948 and is only slightly used. It would be worth serious dollars had it hadn't been fitted with a recoil pad. Doesn't matter though. I still hunt with the gun once and a while. Brings back serious memories for me.
The receiver of these guns were milled out of a single block of steel and the parts hand fitted. Like you said soooo smooth. Its the watch built like a tank. As mentioned, its not the "finest" shotgun ever made but its up there.
When I was growing up, the Model 12 was probably the most popular gun used in Trap shooting. Balance, feel, and durability was of utmost importance and the Model 12 fit the bill. Many others chose the Superposed, but they cost more.