The bronze shells have a more "coppery" color to them while the brass shells are more yellowy.......this is another way you can tell....but if you stated the drum was from 1979 or 1980 it SHOULD be a brass shell NOT a bronze shell, as you yourself just proved that they didn't come out with the bronze shells until 1981. Also, like others have stated, it would have BZ stamped in the shell, not just a B.
Thanks for the info. I was guessing at the date and now think the 3109934 serial number dates it later than 79-80. The other dating detail I believe from Rob Cooks book is that the Blackface P-85 went from 12 holes to 2 holes before 1980 (amazing how long the 12 holes for gut snares hung in there!) and were 2 holes in 1980-1983. Then in 1984 the blackface was replaced in favor of all chrome and the slot instead of holes. So that narrows down the years of mine to 1981-1983.
From an earlier post:
The "BZ" stamp you are speaking of didn't appear until the early 1990's when Ludwig started offering brass shells again in order to quickly tell the difference on the factory assembly line.
This would mean that my 81-83 with a B stamp is bronze would it not?
Whatever....I think I'll just play the thing.