Green’s Dictionary of Slang

(Aus.) a 750ml beer bottle made of brown glass.

1997		West Australian (Perth, WA) 12 Nov. 26/5: The Carnarvon agreement [...] included [...] prohibition on the sale of 750ml bottles of beer known as king browns.
2003		Aus. Word Map 🌐 I grew up in WA and always knew them as king browns, I’d never heard them referred to as tallies until I moved to Sydney.
2011		S. James in Open Writing: Pure Poetry 22 May 🌐 An 800ml bottle is known as a ‘king brown’ in Western Australia, perhaps because when the amber nectar is consumed in large quantities it has a similar neurotoxicity to the venomous snake of the same name.