Nitro turkey shells in a #5....good median between 4 and 6. Primos tightwad choke. That is my 870 setup. My mossberg 500 has extra full choke and Federal Mag Shock. That one kicks like a son of a gun since it is an older gun with the hard plastic recoil pad.
WW HV Supreme 3" # 4s... has 1 3/4 oz of copper plated shot are not too expensive and will flatten a tom at 55yds with my 22" Rem 1187 with Comp-n-Choke.. The 3.5 inch ammo just kicks too much for me to be worth the pain...A turkey at 50 yds is a long ways in a hunting situation. In my experience turkeys are usually in a killable range or not even close, so those big kickers as they say "kill on both ends" and are not needed.