good to hear you like this forum. i'm starting to enjoy it more as i snoop around myself. glad to share with you the knowledge that i have stolen from other people.
yeah, it tilts up like the 1911. it's called the 'delayed blowback' design, where the barrel and slided are locked together either by lugs (2 or 3 in the original browning design) that lock into the inside of the slide or, in our case with the milleniums and 24/7s, the ledge on the chamber part of the barrel that presses against the slide opening.
when the slide cycles back in recoil, it pushes the barrel back with it, only about 1/8 inch or so. you can see this by taking the barrel out and putting the take-down pin in the groove of the under-barrel lugs as if it were all on the frame and then move the pin back and forth axially with the barrel.
then, as the slide continues, the chamber of the barrel falls down and the muzzle rises up. this lowers the feed ramp to the next round making the round more coaxial with the barrel allowing for a smoother feed. if you have a straight blow back gun (my favorite being the bersa 380) where the barrel is integral to the frame, you can pull the slide back and see how high the next round is, nearly coaxial to the barrel to allow a smoother feed.
back to the delayed-blowback. as the slide move foward into battery (slide fully locked foward against the barrel), the slide pushes the round into the chamber, the back face pushing against the back of the barrel 'shroud' and pushes the barrel foward, tilting it back down and the slide locks against the barrel.
it's such a great design, if browning hadn't come up with it, someone surely would have, and the 1911-lovers would be 19-something-else-lovers.