OP, the short version of all this is that there are about a gazillion variables involved in producing a group of shots. The buffer is pretty much at the bottom of the list of variables that would produce the changes in group size and POI you reported. Beyond that, despite several requests, you won't provide any additional information that might help isolate variables.
"Harmonics," whatever that's defined as, and changes in case pressures within safe ranges aren't going to reduce your average group size from .85" to .25," even if you were manipulating them intentionally. There is no way changing buffer weights can do that. That's why everyone is pointing to other causes and seeking additional information. Whatever you observed wasn't caused by the buffer. Regardless, if you really got an average group size of .25" at 100 yards with a statistically signficant number of shots in the groups, you probably ought to leave the rifle as is and stop wondering how it got there because you have a unicorn.
"Harmonics," whatever that's defined as, and changes in case pressures within safe ranges aren't going to reduce your average group size from .85" to .25," even if you were manipulating them intentionally. There is no way changing buffer weights can do that. That's why everyone is pointing to other causes and seeking additional information. Whatever you observed wasn't caused by the buffer. Regardless, if you really got an average group size of .25" at 100 yards with a statistically signficant number of shots in the groups, you probably ought to leave the rifle as is and stop wondering how it got there because you have a unicorn.