Not really. The two components of how far you can consistently kill turkeys with any load are pattern density and the ability of a pellet to penetrate deeply enough to kill at a given range. No doubt Hevi-13 number 5 pellets are going to carry more penetrating power than Hevi-13 number 7 shot. But the pattern density with number 5's is going to fall below acceptable levels pretty quickly.

It doesn't make a tinkers @#^& how thoroughly a pellet would have killed a turkey if it sails past his head and neck 3 inches to the left or right. Or even worse hits him in areas that are not immediately lethal so that he runs off and dies from infection.

Tack a sheet of poster paper on a tree at 60 or 70 yards and shoot at the center of it with a load of hevi-13 number 5's. I'll bet you will see holes in the pattern that you could run a ground hog through much less a turkeys head and neck.