Well, after four years of frustration, I finally bagged a turkey.
For anyone wondering whether two blade broadheads work on turkeys, here a a couple shots of the damage inflicted by a Zwickey Delta.
The shot was a little lower than I would have liked, but the results were devastating. It severed the leg joint at the knee, sliced the breastbone in half, and sliced the liver. He flopped over the bank I was set up in front of. I gave him 30 minutes and found him face down a few yards behind my blind...quite dead.
I washed the blood off of the Delta and it's still razor sharp...sharp enough to pass the rubber band test. I'm done experimenting with other broadheads. From now on there will be a Zwickey Delta on the business end of my arrows.