I have two 20 gauge turkey guns that I experiment with when I want to try something different from the 12's. One is an Ithaca Semi Auto and the other is a Remington 870.
I will break down the 870, if you don't mind.
The gun is fitted with a Hastings turkey choke and topped off with a Bushnell HOLOsight. I shoot #6 - 3" Hevi-Shot through it. The pattern rocks out to 35-40 yards. I doubt I would ever shoot a turkey that far away with it, but it has already dropped a gobbler in its tracks at 30 yards.
It's third gun from the top... The little guy. <img src=icon_smile_big.gif border=0 align=middle>
Jeremiah "Pro"