The effective range is whatever the pattern tells you it is.
Agreed. I use 3 1/2 inch shells because it has been my personal experience that a 3 1/2 inch shell will (despite what some say) usually outpattern a 3 inch shell of the same type in the same gun. I also agree that your maximum range should be the distance that your gun/choke/shell combo will still put 100 evenly dispersed pellets inside a ten inch circle. No turkey head can find a spot to live in a pattern that's still that dense. I also believe in the denser than lead shot if you are trying to extend your range. I know, not I think,
I KNOW it kills farther than lead will.
3 1/2 inch shells aren't that much more expensive than the 3 inch shells especially considering how few of them you will use a year. It's not like we are taking them on a dove shoot here. I can only kill 5 turkeys a year in Alabama so even if I limit out every year one box of ten will still last 2 years.
As for recoil? Yeah it's stout but once the guns been patterned with them all you will every use them for is killing a turkey. And I have never noticed the recoil when I pulled the trigger on a gobbler.