100% fact,your rifle will tell you what bullet and weight to use. The sierra gamekings or a very good starting place. as for WT. the 30/06 start with 165,the 243 I have know idea.Good luckI handload for my guns as well and the best bullet I have found that gives the best accuracy and performance is the Sierra Gamekings. None of my guns like Hornady bullets. It really comes down to what your gun likes not what you like.