I will guarantee remington will tell you a big no. I'm not even a lawyer and I'd tell remington to tell you no.
Now is it safe and will it do harm to the gun are two different questions. I shoot steel in some older guns but they are not quite that old. If, and this is a big if, it is in very good shape a 1930s gun can handle modern pressures. Good shape means no major pits in the barrel and the action locks up well. If the gun has a tight choke, like many older guns do, then it could do harm to the barrel but it would technically be safe. Many older guns with tight chokes that have shot steel will show a slight ring bulge near the choke. That is a big reason why older SxS's with tight chokes should not have steel run through them without being opened up. It doesn't ruin a single barreled gun but isn't helping it any either. It use to be people worried about scoring, that never was a serious issue and with better wads now it is not anything to worry about. The bulge near the choke and just making sure the gun is sound to begin with are what is important.
Me having shot steel in several 1940s and 50s winchesters wouldn't tell anyone else to do it. I would say to be realistic if you do. It is a shotgun built around 1930. Only slower 4s and 6s, no high speed BBs through an old tight choke please.
Tim