These drums appeared in the '82 catalog on page 5 (along with the hammered "chrome" aluminum Supra). The "smooth" bronze made the debut in '81. Also these drums were never listed as hand hammered, just "hammered," as a machine was doing the hammering not an artisan.
After the move to NC it appears that the hammering marks were slightly larger and argualbly more uniformly patterned.
These shells have a high copper content, mine measured at 88.73% Cu | 10.21 Zn, and thus that wonderful hue! Mine is an upside down "B" shell with a mid-80's Chicago Keystone badge - serial number is 3112485 (badge dating is not the most accurate method as we all know these things didn't matter that much back in the day to Ludwig or the consumers). It's also sporting the great twin-channel die cast hoops.