Well @King Fan 's 14-2 Romex-to-bus method works quite well, if I may say so. I got the bare copper out of the Romex, lickety-split. Then I took it down and put it in one of my vise ends of my Sjöbergs woodworking bench, grasping the other firming with needle-nose pliers, and twisting on its longitudinal axis, as @tubeswell suggested. That method works great to straighten it! Then I rubbed it down with alcohol, fired up the soldering iron, and covered it with tin. Now I've got 2 feet of bus bar (I don't know what gauge it is; I'm no good at eyeballing wire gauge) that has already been tinned. It's not perfect and smooth, since you kind of have to "paint" it on with the iron. But it'll work!