The Winchester 25 was introduced in 1949, Where would the line be drawn? The start of the Korean Conflict perhaps? That way Remington 870's would ok, they were introduced in 1950.
All sarcasm aside, SASS shooter both WB and CAS spend a lot of time, effort and money to have gear that meets the games criteria. The Model 12 was shown being used in the movie WBAS is based on.