I never pre-twist the conductors, other than a light twist on a stranded conductor to keep the copper hairs in place.
I have two things against pre-twisting:
1. The taper of the twisted conductors never seems to match the internal taper of the solderless connector. That means the spring has to deform more to fit the conductors, and requires a stronger twist than otherwise.
2. The twisting action of the Kleins on the surface of the conductors work-hardens the copper and makes it harder for the spring to bite.
My preferred splice is to line up the cut end of the conductors, apply the correct size of Ideal Marrette connector, and twist the connector until the wires themselves begin to twist together. Unless nothing else is available, I refuse to use 3M Scotchlok connectors. Absolute garbage.
