Regarding testing loads, if you shoot several few-shot groups with the same load and they're not all the same size, which one are you going to use as the accuracy that load produces? Remember, each group represents what that load will do for a few shots.
It's my opinion that if each group with the same load doesen't have the same size (or no more than a 10% spread in size center to center), you didn't shoot enough rounds to best judge the load's performance.
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master