The 12 is plenty of gun to kill turkeys. I have see a many of tom die at 60 + yards with a 12 ga. The 10 ga. could really destroy a bird that comes in close, heck just this season I saw a client take the head smack off of a tom at about 7 yards. He was only shooting a 3" 12 ga load but had a tight patterning gun. I think having a tight patterning gun and knowing where it shoots is better than just shooting a big gun out of the box. Although the 10 ga will kill turkeys dead as a hammer and some poeple like that, my buddy just sold his 12 and bought a 20 to turkey hunt with because he killed so many with the 12. He kills turkeys consistently because it shoots tight and he knows where it will hit and the limits of the gun, that is probably the most important thing to remember about a turkey gun, knowing its limits.