We've (the family) shot 11 deer with the Grendel (13.5" AR Pistol). Two, hit too far back by kids, were never recovered despite an initial heavy blood trail. The other 9 fell within 40 yards, some in their tracks.
In my opinion, it's an excellent round for experienced shooters who have time to place shots in the vitals. Every deer shot in the vitals was a complete pass through, with a silver dollar size exit wound, except one. That round hit high shoulder, broke the spine and lodged in the flank with about 20 inches of penetration. Deer was quartering towards.
External bleeding is more delayed than a high velocity round. If tracking is an issue, shoot them high shoulder, neck or head. Understand this is not a high velocity round. Stick to soft bullets like the SST and ELD – M and keep your shots within 300 yards. Know that shots in the gut are not going to cause enough temporary stretch cavity/spalling to make an efficient kill.
I love the accuracy and light recoil of the Grendel and will continue to use it to take deer, however, I will choose my shots carefully and make sure the rounds go where they should