For those who are curious about the origin of the term "magnum," bigcountry is correct:
mag·num Audio pronunciation of "magnum" ( P ) Pronunciation Key (mgnm)
n.
1. A bottle, holding about two fifths of a gallon (1.5 liters), for wine or liquor.
2. The amount of liquid that this bottle can hold.
3. A magnum cartridge or firearm.
Mike