I will have to give it to the fighting purr call from Knight and Hale from years ago. For those that don't know, it was two box calls that you were to use and they made an ungodful noise. Probably scared turkeys,
I killed my first turkey when I was 12 or 13 or around there with that call. I remember it was late morning, turkeys had shut up and with hens. My grandpa started calling with those things and they did sound crazy, but in about 5 minutes we had a gobbler on the ground. Turkeys actually do sound like that when they fight (sometimes).
But I will admit, I've never called up another bird with them.