Best to take it to a gunsmith and ask for help.
yes they made a martini action single barrel shotgun 12gauge it is cheap around £100 but it has a huge amount of recoil you can buy them on guntrader.com
Impossible to answer without a DETAILED description of ALL markings, type of action, barrel length, etc..
With the serial number provided,your Winchester model 12 pump action shotgun was made in the year 1949.
I have a sears and roebuck bolt action 12gauge model 58 and numerich arms says the gun was manufactured in 1949
Mossberg
mid 1900's westernfield(mossberg) 12gauge boltaction. in nice condition is worth about 160.00$...up or down.
Need a a DETAILED description of ALL markings, type of action, caliber, type of firearm (handgun or rifle or shotgun),
A shotgun built on a round action.
The Winchester model 1200 shotgun is a pump action shotgun.
I have one ,witch I got in the 1960s-it's not hear so i don't know the serial #-butt it is a 12gauge silver pigeon.
Almost impossible to determine what it is without a DETAILED description of ALL markings, type of action, caliber, type of firearm (handgun or rifle or shotgun), condition, etc
AFAIK they never made a bolt action shotgun