Here's more results with various reloads, and one factory group with Zombie Max. All shot with the GAS upper, 1:7 twist.
Hornady 55gr Z-Max 19.5gr H322, Winchester cases, Federal Primers
Hornady 55gr Z-Max, 20.7gr H322, Winchester cases, Federal primers
Hornady 55gr Z-Max, 21.3gr H322, Winchester cases, Federal primers
Hornady 55gr Z-Max, 21.9gr H322, Winchester cases, Federal primers
Hornady 55gr Z-Max, 23.1gr H322, Winchester cases, Federal primers
Hornady 55gr Z-Max, 22.8gr Varget, Winchester cases, Federal primers
Hornady 55gr Z-Max, 23.7gr Varget, Winchester cases, Federal primers
Hornady 55gr Z-Max, 24.6gr Varget, Winchester cases, Federal primers
Hornady 55gr Z-Max, 25.5gr Varget, Winchester cases, Federal primers
Hornady 55gr Z-Max, 26.0gr Varget, Winchester cases, Federal primers
Hornady 68gr BTHP Match, 22.8gr Varget, Winchester cases, Federal primers
Hornady 68gr BTHP Match, 23.4gr Varget, Winchester cases, Federal primers
Hornady 68gr BTHP Match, 24.2gr Varget, Winchester cases, Federal primers
Hornady 68gr BTHP Match, 24.5gr Varget, Winchester cases, Federal primers
Hornady 68gr BTHP Match, 24.9gr Varget, Winchester cases, Federal primers
Hornady 55gr Z-Max, 22.8gr Varget, Winchester cases, Federal primers
Hornady 55gr Z-Max, 23.7gr Varget, Winchester cases, Federal Primers
Hornady 55gr Z-Max, 24.6gr Varget, Winchester cases, Federal primers
Hornady 55gr Z-Max, 25.5gr Varget, Winchester cases, Federal primers
Hornady 55gr Z-Max, 26.4gr Varget, Winchester cases, Federal primers
Hornady 55gr Z-Max Factory Loaded Ammo #83271