Originally posted by rufe-snow
Sears subcontracted their firearms out from different manufacturers. Probably best if you could post quality photos of the rifle. One of our members might be able to discern who the manufacturer was.
As far as the cartridge it fires? If you have any doubts about the rifle, regarding it's chambering? Take it to a competent gunsmith for a chamber cast, head spaceing, inspection and test firing. We have no way on the net, to answer your question(s) regarding the condition and safety of your rifle.
rufe-snow,,,,could this gentleman be talking about a Sears Model 300 shotgun made by Winchester(that's marked for magnum shells),,????