Thanks for the detailed reply wolf. I was wondering if I was making too big of a deal out of the weight differences, but it never hurts to ask.
With regard to premium vs cheap soft-point bullets...
The main reason I was curious about energy and velocity was not so much a concern about deer, where a .308 is more than enough, but for elk. Right now the 180 grain winchester power points work just fine on deer out to about 300 yards, but I'm guessing that will not be the case if I come up on a big bull at the same distance. A lot of what I have read about the accubonds and Barnes bullets says they're great on penetration but they need to be at a decent velocity if they're going to expand. On the other hand, softer nosed bullets may expand too rapidly or may not stay together when hitting a bone so I would be reluctant to use the power points in that situation.
Another note about my gun is that the action is kind of weird. It's not quite a short action, it's not quite a long action... it's somewhere in between. That being said, the magazine holds 200 grain bullets just fine. Granted they're at a lower velocity than the 180's, and they won't shoot nearly as flat, but would this weight in a soft point or powerpoint still work on bigger, thick-skinned game?