I'm guessing it's a 7mm magnum or some type. My dad hunted for years with nothing BUT the 160 gr. Nosler Partition. Hard to go wrong with that bullet in any 7mm. I use Partitions a lot myself and know you cannot go wrong with them. Another excellent bullet would be a 160 gr. Accubond. I have done water jug testing for penetration, expansion, and weight retention on both Accubonds and Partitions to 500 yards and they both performed perfectly. 160 gr. Partition 160 gr. Accubond Choose the one your rifle likes best.