My wife shot a nice 7x8 NM bull at 405 yds with a 7-08ai in 2015. She used a 120 gr TTSX at a MV of around 3050 fps. Altitude was around 7000 ft. The bullet hit just below and behind the heart and exited. The bull walked about 40 yds uphill and laid down. It took over a half an hour for my wife and her guide to get to the bull. There was no blood trail. He was still alive but was rustling around when they got close to him. She had to put another bullet in him to finish the kill. I believe she would have gotten better on game performance if she's used a higher BC bullet like the Accubond. With a MV of 2920 fps, the Accubond would have been traveling faster than the 120 by the time it reached the bull.
If I had it to do all over again, or if she ever goes elk hunting again, I'll probably go with the 139 gr LRX (wasn't available at the time). Good expansion down to 2000 fps, decent BC to retain downrange velocity and maximize the expansion and penetration of the bullet. But I'd think an Accubond would be another good option for a 500 yd poke. At 500 yds, the 140 would be traveling almost 100 fps faster than a 120 gr with the MVs I used above. Regarding velocity, Barnes lists several powders on their website that provide velocities over 2900 fps with the 139 and 140 gr bullets.
