Geez - I'm getting too old to remember all this stuff. If this twist rate, use this bullet, unless it is copper, blah blah blah. If you need to go through barriers, use that bullet, yadda yadda yadda... What if the situation changes, and I've got the "wrong" bullet?!
My Mini 14 ain't going nowhere, but I'm really learning to like my old-tech (and inexpensive) .30-30. A 170 or 150 gr JSP solves all these issues rather nicely.
As I get older, I'm starting to like bullets that are like me - slower and heavier.