The misshapen pellets become the fliers in the pattern, more pronounced as the range gets longer because there is more time for the misshapen pellets to become fliers, on the periphery of the 2d pattern. How significant that is I can't say. Hunting is a poor, poor way to tell. For example, I shoot doves a lot with my .410s, even though I know they pattern poorly in relation to the larger gauges. However, I kill doves handily with them when I'm shooting well. I once killed three sets of doubles, right then left, on one afternoon shoot about four years ago. I cannot remember when I have ever done that with my larger gauge doubles.
SRH
You are right hunting is a poor way to tell, the reality is if you put the pattern on the bird you will take it down. You are getting the pattern on the bird. However the difference between the payloads in you 410 and the 12 bore simply creates a better denser pattern with the 12. It is not the flyers from shot deformation that is the major difference, it is the number of pellets
