I like Sierra bullets. Many and many a sub-MOA group and many and many a bang-flop--be it Bambi, prairie dog, coyote, feral cat or jackrabbit.
In .223, my choice is the 55-grain HPBT GameKing. Sighted in for zero at 200, about five inches of holdover worked fine for prairie dogs at a lasered 300 yards. 9X on the scope.
Dunno what to say about a rifle. All of mine are last-century--but they still work just fine.