I am a Rem 870 guy, and had to get used to the fact that the Model 12 fore-end had to actually be pushed forward to unlock the bolt from battery. One does not notice that when firing it because the recoil will do it if the shooter has firm purchase on the fore-end. It is really only noticeable if one racks a shell into the chamber and the tries to extract it.
It is a minor difference but it is there. Winchester stopped producing the Model 12 in 1964 because it could not compete, pricewise, with the Rem 870 (initially produced in 1950), which shared many parts with the 11-48, the Model 58 Sportsman, and the 1100 semiauto guns.
Richard, it is still a very good gun and you will like it.
Regards,
Jim