Most of the old Bird' hunters around my area, as I was growing up, used either a pump or auto with a 26" IC barrel., usually a 12. It is I think worth noting that most of these older guns marked IC was actually bored with what should be termed a choke or about .010 constriction.
Although I never kept records as such the gun which I Know I had the highest ratio of kills to shots fired on both Quail & Woodcock I have mentioned here several times before.
It was a Birmingham built & proofed J P Clabrough back action sidelock 12 with 28" Damascus barrels, with both having about .010" () choke. It weighs 6 lb 14 oz & just happened to fit me perfectly. I used 1 oz loads of #8 shot at around 1125 fps @ about 8k psi. These were loaded with Rem Power Piston wads & I never experienced undue mangling at normal ranges for either.
At the time I also did a lot of "Cottontail" chasing with beagles & this same gun & load proved idea for that with the substitution of #6 for the #8 shot.
IMHO a gun bored with .010 choke is good for most anything, assuming appropriate loads, inside of 40/45 yards. I have never seen much need for less & if your shooting calls for more might as well skip to at least a 3/4 choke.
