Go to Dogtags in your profile/stats and there is a "Taken" button/tab. It's easy to miss. It will show you how many times taken too.
And yeah theres still a knife lock on but it doesn't seem so ridiculously sensitive as BC2. Once in that game I locked on and stabbed a guy through a metal crate and many times got kills that I should have been too far away from the person to have it land. And if they are prone in BF3 it doesn't seem to lock.[/QUOTE]
Thanks for the tip, i'll look into it once i get home. Yeah, i've gotten some crazy knife kills on BC2 before too, couple thru walls and doors.