One more time. Thanks Sam!!

Nice! Rick's going to have to put a link to this in the Misc. Good Info thread

It was well received on the 99 Club site, so I thought I would put it here as well. Thanks to Lightfoot for helping with the mechanics of posting.

I am working on another one on the lever, safety slide/latch, trigger and sear.

When you wack the lever and close it with a piece of hardwood to create more friction with the pad on the floorplate it would bring the riding pin slightly lower.
A big mystery of the 99 /1899 is how the bolt manages to stay put and hold . It must be backed up by the back of itself ,hence the change to a rounded bolt at 90,000 and little by the downward pressure of the bolt on the pin that holds it in place that is a part of the lever. From this article, I believe the angle at the back of the frame and bolt is 4 degrees.

Thanks for all this effort Sam, as they've always said about the value of pictures!

This picture series shows in fig 7 how the outside edge of the lever loop begins to engage with the bottom of the bolt, maybe also aiding the push upward, then with the full closure, uses the bump-up shoulder at the outside of the lever loop, (I'll bet You're right, it's the matching 4 degrees!), to help hold the bolt into battery, along with the over-cam leverage of the lever pivot keeps the bolt up, even under pressure!

Note that all this cam leverage changes its direction of pressure as the lever goes through it's arc, as noted in Sam's figure 4&5 comments. I suspect it would take a measureably large amount (..maybe more than equal to backward pressure?) of downward pressure on the bolt to overcome all this lever cam pressure. (i.e. You can't budge the lever by pushing down on the top of the closed bolt, you must use the lever to move the bolt, down then back)

The real miracle of all these mating and moving curves is how little pressure it finally takes to OPEN the bolt and extract an expanded case! This lever function really is one of the beautiful and classic pieces of firearms design and engineering, Bravo!