I think most people choose too much choke and too large a shot size, and would be more successful if they went down in both. Anticipating and gearing up for long shots that Fred Nimrod can't realistically make anyway, means that Ol' Fred misses more of the close shots he had a realistic chance to make in the first place. That's my experience.
A couple of thoughts here: no matter the choke, a #6 shot will fly the same distance no matter the gauge from which it originated incl the 410, assuming reasonably close muzzle velocities and no shot deformation. So while someone may drop a bird at 65 yds “right there”, one is much more apt to miss or drop him a mile away with one shot in his guts. All other things about equal, the gauges distinguish themselves by the max range they produce a lethal pattern which of course becomes shorter with each step down in ga. from the 12 gauge assuming standard upland loads, say of 2 3/4”. This might be compensated somewhat in the smaller gauges by dropping “up” in shot size; i.e, 7 1/2’s in a 20 instead of 6’s used in the 12.
And I agree, I may go “down” in shot size but up in payload in a 12 on late season pheasants depending but usually stick with 6’s in my 20. I will take the denser pattern in a 20 over fewer but larger shot and maybe a little more ratty pattern. I’m speaking exclusively for pheasants. I don’t have empirical evidence for this tendency but it makes some sense anyway.
I alluded to the the NW Iowa pheasant culture in the 60’s and 70’s which held to a 12 gauge, full choke barrel, and #4 shot. for pheasants. On probably 90% of the shots all of this was counterproductive or a disadvantage. However one thing to remember too is shotshell evolution and the great improvements that have taken place. I wonder in today’s shells if 1 ounce of 7 1/2’s out of a 20 might not have beat an 1 1/4 oz load in an old 12ga paper shell without an enclosing shot cup and an over-the-top round wad going through a full choke.
Like the mono- bullets in big game cartridges have done, today’s shotshells may have lifted each gauge’s effectiveness to the level of the one’s above it fifty years ago.
