07/16/2021
The "2 and 1 Phenomena"
Those of us in the precision shooting world eventually run into the situation where multiple shots form a nice tight group then, in some random order, a “flyer” forms just outside the tight group (this assumes no known cause of the flyer). Changing every front-line system variable (bullets, powder, primers, COL, trigger pull, rest, etc., etc.) and even shooters will reproduce the same outcome, a very nice group and proportional flyers (surprisingly in the ratio of 2:1 in my experience- although not scientifically proven). Even with the flyers, groups were ½ moa. Good enough for my personal limits but most in this industry love to tinker.
A few years ago this happened to a shooting colleague and I and we were determined to find the answer. I feel we asked every professional in the business and surprisingly we lacked good answers. If you google this situation, you find a little discussion on it, but not as much is I hoped. This lasted about 1.5 years.
One can take this stuff down the rabbit hole as deep as willing and we tested a lot of combinations. In the end, it was neck tension with a splash of concentricity of bullet seating. What fixed the 2:1 problem for us we a match seater die and changing brass that had uniform neck wall thickness.
So there it is, by no means am I saying your situation may end up differently, but start here.
