I have used 200 gr Accubonds at about 3150 FPS with Retumbo in a 300 RUM. I have not shot an elk with that combo but I have shot two moose, both within 50 yards. Both moose took more than one bullet and, on both, at least one of the bullets came apart and failed to get good penetration. I just don't think there is a bullet out there that will perform perfectly, all of the time, from close range out to 700 yards or beyond.
I would reccommend the 200 grain Nosler Partition for 0 - 700 yards at your 3150 FPS muzzle velocity . It should penetrate , expand , and exit at those yardages .
I have experience with the 180 grain Partition , at 3200 FPS from a .300 Weatherby , and a very large Black Bear back in 1973 .
150 yard shot into front of left front shoulder , and exited out of right rear hip . Broke LF shoulder entering , and broke RR hip exiting , and made a mess of vital organs .
In 1988 , I shot a spike bull Elk , with my 7mm Rem. Magnum , running 150 grain Nosler Partitions at 3210 FPS , at a distance of 75 yards . The Elk was quartering away from me moving from my left to right , and I was aiming behind it's RF shoulder . However , just as I squeezed the trigger , my friend came running toward me from the left , and the Elk spun quickly to it's left , and I ended-up with the proverbial "Texas Heart Shot".
The bullet entered 1" above the rectum , through the pelvic bone , into the spinal column taking out more than 24" of spinal vertebrae , then through top of the right lung , through the RF shoulder , finally coming to rest just under the skin in front of the right front shoulder .
All total , over 4 feet of penetration , and recovery of the rear partition and core .
The elk dropped on the spot , although I did walk up to it and fire a finishing shot .
I also shot a moose with that 7mm Rem Mag , 150 gr. Partition , at 60 yards , broadside shot entering through LF shoulder , exiting through RF shoulder . Moose dropped in it's tracks .
The Partition will reliably expand , then loose the front mushroom , and retain 65 % of it's weight in the rear of the bullet , behind the partition .
Exceptional bullets , just not a high Ballistic Coefficient .
Also , all of the Partitions that I have used have been very accurate .
.243 Win , .25-06 Rem , .270 Weatherby , 7mm Rem mag , .300 Weatherby , and .340 Weatherby .
DMP25-06