Press grip width 'vertical forearm' clarifications

[BigHig]

As far as I can tell, this has not been addressed on the forum or in the book.

All material I can find recommends a press width which places the forearms in a vertical position at the bottom. This is clear enough. However, there is a large variation in grip width which can produce vertical forearms, depending on the shoulder's rotation, and the distance between the bar and the neck. For example, I could place my hands directly in front of my shoulders with an extremely narrow grip, such that the humerus completely obscures the forearm when viewed from behind, and the grip is completely off the knurl, and the forearms would be vertical. I could also take a very wide grip with my shoulder externally rotated to almost 90 degrees, and my forearms would also be vertical. Now, I understand that we want to reduce the moment arm between shoulder and hand, and therefore the wide grip is bad; however, all videos I've seen on the subject do not narrow the grip as much as to place the hands directly in front of the shoulder. The grip width in the video tends to align the thumbs with the outside of the shoulder.

From what I can tell, the ultra narrow grip and the standard grip have the same moment arm between hand and shoulder, and between elbow and shoulder; the arm is flexed fully in each, and so the only difference in moments is that the former places the bar further forward, requiring a more pronounced backward lean to keep it over midfoot. But because we are already leaning back in the press motion, this is not necessarily bad. Despite the bar being more forward of the neck, the moment arms about the muscles involved in the lift are actually the same.

Is aligning the thumbs to the shoulder the official recommendation? If so, why; what is the heuristic? Is it that we want the smallest moment arm and the least lean necessary? Or is it that we want more medial deltoid recruitment, and the very narrow grip is more isolated to the anterior deltoid?

[BigHig]

I realized that this question can be very briefly stated this way: "What is the correct angle of the humerus, relative to the sagittal plane, at the start position of the press?"
I've seen most materials put it around 45-60 degrees, and I'm wondering what the downside is to an angle 0-45 degrees.

[Mark Rippetoe]

Better: What is the correct distance between the bar and the shoulders in the sagittal plane in the start position of the press?

[BigHig]

Better: What is the correct distance between the bar and the shoulders in the sagittal plane in the start position of the press?

At first I thought it should just be as close to the shoulder as possible, but if it were directly at the shoulder biting into the neck, it would take a very large amount of leanback to clear the chin. Every inch it floats in front of the shoulder requires some leanback as well to keep it over midfoot. So probably the correct distance between bar and shoulder is that which causes the balance lean to also be the clear-chin lean and minimizes them both; maybe 2-3 inches in front of the shoulder. That's if we are trying to strict press and lean as little as possible. For the press technique with hip involvement, I imagine it should be somewhat closer, but still not biting into the neck due to the chin issue. So I think basically just about where the book recommends it.

[JJ23]

I find it easiest to press with the bar as close as possible.