Bullet WEIGHT means very slightly more than NOTHING when it comes to stability and twist rates, so get that out of your head. People who talk weight: 1) don't know chit. 2) are making a very generalized comment.
RPM is what stabilizes, and the LENGTH is what needs stabilizing, not the weight.
RPM is a function of both twist and velocity. No two barrels are created equal, but here is a calculator to get you started:
http://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi
Look up your specific bullet from the tab on the left, then come back and fill in for your specifics.