I need a rifle for shooting Nilgai while both they and I are on the move. Being a large antelope, I need a caliber big enough to go all the way through and leave a blood trail. Since both parties are moving at times, the more rounds in the magazine the better. We lost a large cow this weekend hit broadside while running with a .270 shooting Nosler partitions. Zero blood trail. We then took a small cow and cut out a .270 that hit it broadside but stopped just inside the skin on the exit side. The 458 SOCOM has some nice weight to it but I don't know if it has the punch to get all the way through the animal. The Armalite AR10 Ultramag is close with the .300SAUM round but the 24" barrel is a bit more than I want and the 5 round magazine less than I want. I like the .300WSM for the added punch, hot round, and reduced kick for less muzzle rise while firing multiple rounds, but haven't seen much available. I have seen Noreen ULR rifle in .338 lapua and .300 win mag but as mentioned before, the less kick/muzzle rise for follow up shots the better. Simply (sarcasm), all I need is a AR15 with a Surefire 60 round magazine with an Eotech firing rounds that will completely pentrate a 700lb animal. Any thoughts? Thanks.