Hello Mat as brian says above it's best to plunge into allready melted brass in the crucible,I never ever melt swarf down,only solid brass & never just melt down to make ingots, I don't think it does it any good re-melting it as you can boil out the zinc , i remelt alloy though, I use salamander suprex crucibles for brass & alloys but if I need larger amounts of alloy I use a steel pot, suitably coated with refractory wash as molten alloy dissolves steel as well as becoming contaminated,brass is not allways an easy metal to cast, allthough there's some clever casters on youtube,there's loads who melt[or "smelt" as they like to think they are doing] wearing shorts & flip flops then pour into tart tins & followers chuff them up for being so clever, well anyone can melt a pot of alloy but it's the "gentle art" of persuading it to properly fill a mould is where the skill lies.
Graham.