Try gun shops, pawn shops, gun shows, e-gunparts.com
your model 12 Winchester pump shotgun was made in 1951 as to value in fine condition I have seen them from 550.00 dollars and up.
This fine old shotgun was made in 1902.
There are several types of gun stores that sell parts for different types of shotguns including models by Western Field. There are also online retailers like Amazon that sell these parts.
It should fit , you may have to do some fine tuning . If you look atNumrich gun parts site the mag order # is the same for both guns
The winchester model 42 slide action shotgun was made from 1933-1963,with a total production fiqure of 164,800.your winchester model 42 shotgun was made in 1937.the value of these fine shotguns based on the standard model is between 1,200 dollars for a shotgun with 60%original finish remaining,up to 1,975 dollars for a fine example with 95%original finish remaining.Prices could be higher if you have a solid rib barrel,or a skeet grade,trap grade,or the deluxe grade shotgun.
I would try Numrich gun parts corp.They may be found on the web.
numrich arms
At this time no,there are not any available.You could have a model 1300 slug barrel redone and have the gas ports added to this barrel.Then it will work fine in your model 1400 Winchester shotgun.
I see no reason that you cannot.The steel shot sould work fine in your ranger model 120 shotgun.
Fine
I own a London Fine twist double barrel shotgun in fair condition, it was rated at $100.
If your Winchester model 1897(not a model 1987)is a standard grade field gun?I would say the value of your shotgun would be between 150 dollars for a gun with 10% finish remaining up to 550 dollars for a fine specimen with 90% of the original finish remaining.