Thank you Allan, it sounds like you are a real Benjamin aficionado! If you have any photos of your 312 and 347...
I've just found a BB Pelletier article on the 397C - I'm learning a lot today.
GS392/397 reminds me of my Sheridan Model F. With CO2 rifles, I have a feeling that my Crosman 160/180/400 are hard to beat. But who knows!