Its the pump handle that makes the difference...(total guess!)
I have the same EZgrip on my S6 and it also seems to feel just that bit smoother than the other S6s at our field with the standard pump handle...
Don't know why, Don't even know if it possibly true...Maybe it is purely the ergonomics of the handle...I don't know, but it does feel good!
Also, I have been shot with that gun Broch.
My business card says "Your in luck, I do two things..."