Catfish and Mikey bring up a couple of good points, in their disparate views on bullet weight. I hope they are up to being singled out. :?
One is, that there is a large pool of experience out there, for us to draw on. Most all of them vary, and seemingly similar situations may have widely separated conclusions.
Another, we all will draw our own conclusions, to a degree. And, seldom are they the same. We can share experience, but the choices remain your own.
My question to you, and it ties in with Jason280's,
Do you think it is better to sacrifice some velocity and trajectory, in order to use a heavier bullet? Now I'm not trying to compare 125gr bullets against 200 grainers, but bullets that are similar in weight. Say 148gr vs 158gr., or 180gr vs 200 gr. I don't want to start any sort of argument, but I have been wrestling with this problem myself. I wanted to use a 180gr cast bullet in my .357 Herrett. It does better with the 200gr bullets, but sacrifices a little velocity. It gives up what I would call a significant amount of point-blank-range.
If I didn't want the extra velocity and flatter trajectory, I could have stayed with the Mag/Max. By using a heavier bullet, the vel/traj figures are the same as with the smaller cartridge, albeit with increased energy at all practical ranges.
I haven't resolved this issue to my satisfaction, yet. I would certainly appreciate y'alls input. And NO, going to the 358 JDJ isn't an option right now!
BTW, in answer to Jason280's second question: Yes, you can drive a cast bullet faster than a jacketed bullet, at the same pressure levels. BUT, everything has to be just right, and it won't be by any significant amount.