Hi! Im building a creed and wonder if im going to gain anything by using slower powder Than RL17? Like norma MRP or vihtavouri 560. If so I would set barrel for 2.950 OAL 130-140 grains bullets touching lands at that oal. With an OAL like that i would get plenty of room for powder but Will i get moore speed than 2850 oal and rl17?
Regards
Regards