Twisted 28gauge dual nano coil around a dart tip I'd hazard a guess and say 7 wraps would get you there.
Just made one not 5 minutes ago (5 wraps to get 0.3 ish) and boy oh boy is it tasty. Tried a 0.3ohm non twisted 28gauge last night but didn't work too well and kept burning juice. Twisted is the best thing I've had so far.
Some before and after shots for ya Can't believe they came out at exactly the same resistance!