Thanks for a very informative thread -- text, pictures, and discussion. 

I'm planning an approach graft on an Austrian pine (Pinus nigra) this weekend. This information will be very useful.

Austrian isn't JBP, but both are two-needle black pines, and there's not much specific info available on Pinus nigra. (At least that I've found.)

All but one took, the one destined to be a new apex.  It looks to have been too shallow and pushed itself out as it swelled.  I've recut and tried again already.

I'll try to get pictures when it's not a billionty degrees outside.  They keep talking about a cold front coming through which should get us back into the 90s.   

Just tweezers at the moment. I left a few candles in the back for grafting next year. We'll see how he does then.

Instead of starting a new thread, can anyone advise what part of the year should approach grafting on JBP be undertaken?

The grafts seem to have taken nicely.  They've been separated from the parent branch and are quite vigorous.