I have a Mossberg 835 using a Indian Creek Turkey Choke, I have 2 boxes of Hevi-Shot 13, 3.5", 2-1/4oz shot, in #5, with the same ammo but in #6 will you think I will see a huge difference in performance?

I'd say yes... The 6's will prob shoot a lot better

I'm a 6 guy myself but only because my Encore loves em. You'll have to shoot em both and see. Personally I think the 6's will shoot better.

Dan

What is your definition of performance?

Are we talking about # of pellets in a 10" circle at 40 yards or are we talking about how far it'll knock a turkey off his feet?

Ain't no doubt that a larger pellet is going to hit harder... thats common sense. And there is no denying that if you want to put a lot of pellets in a circle (which will eventually hopefully be a birds head), then there are naturally more #6 pellets in 2 1/4oz of shot than #5 pellets.

Personally, if #5 pellets are giving you good results out to your maximum desired range, I'd leave good enough alone.

I am seriously contemplating going up to #5 or #4 this year.... I shoot birds in close, so it really doesn't matter, but since I'm not shooting at a range where I have to worry about my pattern opening up too much, I might as well have a little extra whallop. But I've never had the first problem with #6s in lead or in Hevi-13 or Extended Range HD.

More than likely the only difference you will see is a more dense pattern with the #6's. If you are worried about terminal performance the #6's hit more than hard enough at 40 yards (and beyond) to cleanly take any turkey alive