Jack is a very rugged, immense mountain. Much of the scrambling is reminiscent of Ragged Ridge, crumbly and easy to dislodge rocks of all sizes. I’ll echo what has been said in other trip reports - being a helmet & probably don’t climb this thing if anyone else is on-route. You’re exposed to rockfall as soon as you begin the traverse across the face.
That said, it was fun to push myself as this has been on my list for a few years now. Followed the route that Jason & Nathan submitted. I also waited until later in the season for less snow on route and was able to avoid travel on the Jerry Glacier altogether by passing below it. This trade for less snow presents another problem of loose rock on the traverse. Pick your poison sort of situation.
This is a pretty serious undertaking so be prepared for it to be rugged and loose!