I did alot of experimenting on this very subject early this spring. the best combo i came up with was this. I had a New England youth model single shot. I wanted to get it ready for my daughter for youth turkey season. It is a fixed Modified barrel. I was afraid i couldnt find a suitable load to satisfy me, and actuallt get it to not hammer her..Well i tried a bunch of loads. And i finally decided to break down and try some 2 and 3/4 loads cause i was afraid the 3 inch loads just kicked too hard. So i went and checked the selection at the sporting goods store. I picked up a box of Winchester 2 and 3/4 super pheasent number 6s... They came in a box of 20, and i believe were right around 20 bucks.. So i shot it at 30 yards just to see, at it patterned awesome. Velocity was right around 1330 i believe... My 3 inch 12 gauge hevi shot is only 1050 i believe.. Plenty fast enough, and patterned great out of her gun. I would not hesitate to shoot a turkey at 30 yards with it..
And of course i had to work both days of our youth season so i didnt get to take her. And honestly im thinking about buying myself a 20 gauge to turkey hunt with, cause my bad shoulder sure doesnt like that 12 gauge kick..