Well there is no Remington Model 12 shotgun, a model 12 is a 22 lr, they did make a smoothbore but it would have said so. A smoothbore model 12 is rare and valuable but I doubt that's what you have if it doesn't say smoothbore it's probably shot out.
nib $450
The shotgun is like new..
Try posting at Remington Society of America.
in good condition around $225
30p
75-400 USD
800
Tough question, the Remington model 550 is a .22 rifle not a 12 gauge shotgun.
anywhere between $750 and $1400 (NIB)
Remington did not make a "Wingmaster" shotgun in 1936. The Remington Wingmaster (Model 870) was first introduced in 1950. remingtonwingmaster.com
100-350
100-300 USD