Great advice and explanation Steve. Now tell us what to do if it is a bit too tight as sometimes happens if it is too large the first time.
Thanks,
Bennett
Wow, How did I miss this since the 18th of March.........................

Mark has got the stretching method down pretty much. The only thing I would add is to anneal the wire before stretching. I use a ring mandrel and a leather mallet for that.
On one that is too large, well..................you've just got to guesstimate on how much to snip off the twist. Cut it at the solder joint and then snip off a bit - re-solder - and dry fit. It may take several times to get it to your satisfaction. I prefer this to stretching.
Another little hint: The ends of the twist very seldom match up so take your pliers and twist the twist wire tighter a little until the individual strands line up. File both ends flat and solder - sparingly.