I used 120 Nosler Ballistic Tips (2nd best on game), 120 ELD-M's, 130 grain Sierra Gamechangers, 100 grain Nosler Ballistic Tips, 120 grain Sierra Pro Hunters, 129 SST's, and 120 grain Speer Gold Dots. The 130 Gamechangers probably did the best job in terms of distance traveled after the shot, but they still left no blood on the ground at all. The Gold Dots did the worst of the bunch. Pencil holes at 80 and 110 yards on a pair of does, zero blood. One doe ran 100 yards and the other almost 3x that far. Nearly didn't find that one.
After over a dozen animals, I put the Grendel squarely in the .223 category on game. Not for me, but some guys love it. To each their own.
The 7.62x39 is in another league in my experience.