Winchester was indeed the company....
For a model 12 collector, a pigeon grade trap, with a white hydro coil stock is just about the "holy grail" of M12's. Some thing like less than 100 were produced, and I know of one that has the only hang tag correctly marked for the gun in existance.....Nope not mine, but I wish it were!
Estimated value approaches $20,000, for a pigeon grade trap, in the box with papers and the hang tag.
They worked well for a while....the oil filled shock absorber would eventually wear out. There is a new one being made on the market today, if I remember correctly.
Best regards, Kirk
PS.. Winchester sold these stocks for installation on existing shotguns, actually quite a few too. So just because a shotgun has one, this does not mean it was originally sold that way. Not a collector either, if installed later.