I rarely use any call to shock gobble, but when I do it's a crow call. I crow call just enough to get the real crows going and then let them take over. Gobs will respond in the spring to crows where I hunt. In the spring when they're hot, Gobs are wired to responding to just about anything.
There's something about the relationship between crows and turkey that I'd like to understand better. Maybe there's a love/hate relationship. Crows will harass turkey -like they do an owl. But perhaps crows wait for turkey to identify and kick up insects, seeds, etc.
I'll start another thread on the relationship between crow and turkey.