My G29 and G30 both "auto-forwarded" pretty consistently if the mag was seated briskly; of course, in both cases a full mag weighed almost as much as the empty gun, so there's probably a Gee-Mister-Wizard inertia explanation at work.
I viewed it as a defect, actually.
(My Mauser HSc auto-forwarded, too, but it was supposed to. )