The Mossberg website states the Turkey Thug has
"Chokes : Ext Turkey Tube "
...The National Wild Turkey Federation. states that it has .665 choke diameter.( 12 ga. )
And I see where it's written that I shouldn't shoot ANY steel shot thru such a choke .
"Pay close attention to the amount of constriction the custom turkey choke has built into its design. The more constriction, or tighter tube dimensions in the choke, the longer the range will be in general. Chokes that measure .600 tighter are long-range systems. When the choke is more open, say .500 or less, the range become shorter in terms of an effective pattern.( again , refers to 12 ga. )
But make no mistake, a shorter range can mean better payload control. What you need to decide is how far do you want to shoot at a bird? And what is the best distance with that choke.
For example, a .669 choke will shoot a baseball pattern at 25 or 30 yards. Missing the whole bird is a real possibility here.
At 40 to 50 yards, that ultra tight pattern will open more and become a deadly killing machine about the size of a basketball. "
Read more:
http://www.gameandfishmag.com/2012/04/19/selecting-the-right-turkey-choke/#ixzz30a49TyZe