wild willy,
The composition for cartridge brass is:
copper, 68.5 - 71.5%
lead, 0.07% maximum
iron, 0.05% maximum
zinc, remainder (100% minus the sum of the previous 3 metals)
Ammonium Hydroxide/ammonia vapors are well-known etchants for copper/copper alloys and leads to embrittlement of the grain boundries because it is there that the etchant attacks most readily.
Take my word for it.....keep cartridge brass and ammonia away from each other! You don't want a cartridge to blow up in your chamber!
Jim: retired metallographer