Same shot size, same speed = same distance no matter the gauge. A load of #7.5 or #8 or #9 out of a .410 and a 12ga travel the same distance.

Aside from the differences of weight of shot load, and powder charge; the effects of speed, air resistance, wind and gravity affect each pellet the same way. We did a demo of this a few yrs ago at my local skeet range.

We demo'd .410, 28, 20, 16 and 12 all loaded to the same speed. There wasn't a real difference in distance.

Then I ran a Rem. hevi-shot in my beard buster.....I killed that cardboard deader'n a hammer at 55yds.