So here is the bullet I have found to be very effective out of my 270 on elk.
I am using the 140gr Interlock BTSP, from hornady product #2735. Last year, I took 3 shots at a wounded (by another hunter) cow elk at 380-400 yards with this bullet out of my 270. The results, all three hit in the pocket behind the shoulder, all three were lodged in the far ribs, The expansion was good, and the bullets averaged about 86% wieght retention. My wife also shoots this round. The first year she shot a big cow in the shoulder at about 230 yards. The bullet blew up the etnrance shoulder, passed through and broke the second, lodging just under hide. That bullet has 83% retention, after breaking 2 shoulders.
I am a big fan of the 140 gr BTSP interlock.