Yeah, those are dead on. So there's your answer BigUglyMan of why people would burn so much more powder--because you have to in order to get those velocities. If you aren't needing to pound your bolt open with a hammer after each shot, I'd suggest trying a different chronograph. Maybe your co-worker with the slow 300 RUM would let you shoot over his?
This all assumes, of course, your aren't using a 38" barrel or something.